Modified engine transfer issues

This sounds incredibly silly, but I am attempting to port map files from Medal of Honor: Allied Assault (which uses the .bsp file format and uses a heavily modified variant of the engine used in Quake 3) to Hammer to then port to Garry’s Mod simply to screw around with. The tools I’ve attempted to use to do this simply do not work. gtkRadiant does not acknowledge it, nor does TrenchBroom. I believe I found a tool at some point that enabled me to load the MoH:AA .bsp files, but what it was is lost at the moment. The only tool that’s worked is a one, but attempting to load this into Hammer or the aforementioned other tools have simply crashed or not worked.

Would anyone happen to know of any tools or ways to do this?