Hi again. Ok, answering my own question, in case it will help anyone else:
Apparently, I just needed to play around with the PACLED64.exe app for a bit (not the most intuitive, but fairly simple once you understand a few basics):
1. I'm using a controller called the Ultimate I/O made by Ultimarc. They have others that may work with this program as well, this is just what I'm using.
2. RGB LED's have 3 LED's in them, Red, Green, and Blue. The combination of these individual LED's and their relative brightness, determines the overall color of the RGB.
3. Each LED has to be individually addressed and it's relative intensity (from Zero/off to Max) has to be assigned, to get a particular color.
So for example, to make an RGB button look "Red", you would turn on Red (set it to some value from 1 to 255), and turn off Green and Blue.
Blue would likewise be Blue = On, Red and Green = Off (value of 0). All other colors are a combination of this basic principle.
You can easily google "RGB Code" and it will show you the various combinations and intensities for colors you want.
4. Each RGB has 4 wires - Ground, Red, Green and Blue. These connects into a 4-wire section or pin layout on the controller, where the 1st wire is always "Ground", and the other 3 are the Red, Green and Blue, respectively. Each of the pins that these colored wires connect to, has a separate numerical value. Your goal is to have the controller feeding the right intensity signal to each colored wire, for each RGB button, to give you the color pattern you want.
Because the "ground" pin or wire isn't counted, you only have to think of the color outputs when figuring out their numerical value.
Player 1 Switch 1: Player 1 Switch 2: Player 1 Switch 2
Ground ----------> ] ---Ground Ground ----------> ] ---Ground Ground ----------> ] ---Ground
Red ----------> ] --- Pin 1 Red ----------> ] --- Pin 4 Red ----------> ] --- Pin 7
Green -----------> ] --- Pin 2 Green -----------> ] --- Pin 5 Green -----------> ] --- Pin 8
Blue ----------> ] --- Pin 3 Blue -----------> ] --- Pin 6 Blue -----------> ] --- Pin 9
And so on.
Example, for the 1st 4-pins (or output ports if your board is more basic), which are Player 1 Swithc 1 in this example, pin 1 corresponds to the Red LED, 2 to the Green, and 3 to the Blue. The second four, Player 1 Switch 2, are Ground, Pin 4 (Red) Pin 5 (Green) and Pin 6 (Blue), and so on.
Oddly (not sure if this is my board, or more universal), this pattern reverses for pins 49 onwards. So pin 49 is now Blue, 50 is still Green, and 51 is now Red. This will matter later (see below)
Ok, so now you know the basics. Play around with the utility a bit if you want. You have to have power to the controller, AND have the micro USB cable connected to a USB source (for now, that USB source is your PC, but later, it can be your MISTER, Rasberry Pi, or whatever It just has to detect that there's something plugged in).
Run the PACLED64.exe utility. You should see two green bard at the bottom of the utility if you have the basic wiring set up correctly. One should say "DIRECT MODE" and the other should show the controller board that it recognizes (in my case, the 2nd bar says "I-PAC UIO FOUND", but this could be different depending on what controller you're using.)
Select "Clear Flash" to erase any previous script (including the factory default script) that was on the ROM. Don't worry, there's a button to "Restore Factory Script" if you want it back.
Tab over to "Brightness". This is where you will specific the combination of address and brightness level for each button you have.
You enter the numerical address of the pin you want to set the brightness for, and adjust the slider bard to the level of brightness you want. I wish there was a way to enter this numerically, but apparently there isn't, so just make do with what you have.
Once you've entered your pin code and brightness level, click "APPLY", and your RGB should change instantly. Of note, the "Apply" button only becomes selectable if there's been a change to the brightness value (slider). So for the next pin, it's not enough to change the number, you also have to move the brightness slider around to get the program to register that you're entering a different value. Tedious, I know.
So let's say you want the 1st RGB button to be red, the next green, and the next blue. It'll look like this:
1, 255 Brightness -> Apply
2, 0 Brightness -> Apply
3, 0 Brightness -> Apply
4, 0 Brightness -> Apply
5, 255 Brightness -> Apply
6, 0 Brightness -> Apply
7, 0 Brightness -> Apply
8, 0 Brightness -> Apply
9, 255 Brightness -> Apply
And so on. Also, at least for my board, this address pattern changes at pin 49, where 49 is now Blue, 50 is still Green, and 51 is now Red.
If you want all the pins set to a certain value, you enter "0" for the pin number, and once you set the brightness, all the LED's (and therefore, all your RGB's) will be set to this brightness level (this is as close to "white" as they get - light violet to my eyes).
Below, I'm breaking it down to the steps I had to take to get my 2-player setup to have Red buttons for player one (whose buttons I plugged into pins 1-24) and Blue for player 2 (whose buttons I plugged into pins 49-72):
1. Make sure you have the utility that Ultimarc publishes for controlling and programming scripts for LED control. You won't need to run this once you have your RGB LED's running the way you want, just to program the scripts. It's available at this link: <a href="
https://www.ultimarc.com/PacLED64.exe">PACLED64.exet</a>
2. Install it on a PC, and launch it
3. On paper, map out your LED layout. You'll have to do a lot of precise address/brightness entering, so having it on paper in front of you reduces errors and having to restart.
4. Plug in your Controller's power and connect it via USB to your PC.
5. in the Utility, "clear flash". Then tab over to Brightness, enter "0" and set brightness to Zero, click "Apply"
6. For my layout, every 3rd key starting with 1, was Max brightness. This ended up giving me all reds for player 1, and all blues for player 2 (remember, my pin address changes at key 49).
7. Go back to "SETTINGS" tab, click "Start Recording Script".
8. Go back to "BRIGHTNESS" tab, and enter "1" and slide to max, Apply. Next, "4", max brightness, Apply, and so on, until you get the buttons set to whatever you need. Note, if you want different color combinations, then do it your own way, as long as you understand how they are mapped).
9. As you do this, you should be seeing the buttons lighting up the way you want, as it's both recording the script, and executing the command, at the same time.
10. Once done, go back to "SETTINGS", click "Stop Recording Script".
11. Click on "Run Script".
12. Now, unplug both the power from your Controller, and unplug the USB cable from your PC.
13. Plug the USB from your controller to your MISTER.
14. Power up your Controller and your MISTER. Your RGB lights should be working on their own now, without needing the PACLED64 utility running.
Hope that helps, good luck!