You need to have the wad files in the same directory. I encountered the same thing.
I cant seem to get mods to work though, or any command line arguements, and it crashes almost as soon as it launches. Also it only displays the image in top half of the screen a bit squashed (I think its trying to use one of my weird, designed for mame p96 screenmodes).
Any pointers would be appreciated.
@XDelusion
Glad my ab3d mod idea stuck. I cant seem to shake it either.
Any recommendations for editors and whatnot? I'd like to do the whole thing from my amiga and/or amithlon box though, which limits me to amiga tools, or DOS tools (for running inside pc task).