>It looks like I'm lost. When I add it to config.fp menu can't be generated (menu option "Generate" appears disabled).

Make sure that path to GenMenuX in config.fpw is correct. If it's not Global system variable _GENMENU will be empty in VFP.

>All document i've read about Genmenux mentions "Genmenux drivers" like *:MNXDRV1, where can I find that?

You don't need those drivers in your case because you use GenMenuX basic functionality.