Sure. Here's an example of the script. The way I have it, it's intended for the marquee monitor to be positioned directly above the other monitor in the Windows display settings but if you research the splashimage command online or are already familiar with it you can adjust the numbers to make it work with the marquee monitor positioned anywhere. I was able to get it working mostly fine with different width resolutions but I have one game that switches the resolution of the primary monitor and something was causing the marquee monitor to chop off the end of the image with that game and setting both monitors to resolutions with the same width was the way I fixed it. If I remember right, this method doesn't preserve the aspect ratio so the image needs the same ratio as the monitor's resolution or it may get distorted. I've been using the PCLauncher module in rocket launcher to launch these but I'm sure they could just be launched directly from AM.
SplashImage, C:\Emulation\RocketLauncher\_Media\marquee\tekken7.png, b t +x +y-810 w1920 zh-1 zw1920, ;displays the marquee on the marquee monitor. You can substitute the "+y-180 w1920 with the height (y) and width(w)of your montor.
Run, TEKKEN 7.url, C:\Emulation\RocketLauncher\_Launchers ;launches the game from a desktop shortcut. Use .url file extension for steam games and .lnk for gog games
Process, Wait, TEKKEN 7.exe ;waits for the games process to exist
Process, WaitClose, TEKKEN 7.exe ;waits for the game's process to close
SplashImage, Off ;removes the splash image from the marquee monitor
I think I'll mostly just use the built in feature from AM from now on since it works pretty well for me and is a lot less work, but this AHK method could potentially be modified to allow you to switch between a marquee and some other image like a moves list for a fighting game using a joystick command. I was thinking I might try that for certain games at some point down the road.