Ok, so I change the name of col.gba to col.mb, so that it runs .col files. When I run a .col file, the emulator boots up fine, but after that I get a black screen. If I hit exit in the menu, the BIOS actually shows up properly, giving the "turn the console off" message. The ROM that I am running is Jumpman Junior.col, which I padded the size to be 65536 bytes, so that it actually boots.
Edit: I renamed it to col.gba and it works fine.