How do you add new emulators?

[CrimsonGhost138]

So I want to use Mesen to emulate my NES, Famicom, and FDS systems but it's not in the global emulator list. I added the emulator to the global emulator tab in RL and modify a Fceux AHK file for a module but can't quite get the bugs worked out. I've been pulling my hair out trying to get this to work so any help would be awesome.

[hassen]