Which are exactly the same as the versions on http://wolfmame.marpirc.net/ (since MARP links directly to them). There is no frontend (other than a very basic Tcl/Tk one that I wrote and no one cares about).
If you're using playback.bat to play back an INP, the syntax is: playback gamename INPfilename [any extra options you want] The INP filename should not include the .inp extension, the batch file does that for you.
If you're not using playback.bat (which is entirely possible): mame gamename -playback INPfilename [extra options] In this case, you must add the .inp extension, as MAME does *not* do it for you. And it will help to remove any NVRAM/DIF files relating to the game you're playing (again, this is something that playback.bat does for you).