It hasn't been explicity tested with the Vex kit, but it's compatable with IFI Loader. I think Vex uses IFI Loader, if so, then it should work.
As for mcc18, it runs fine with wine. I haven't tried MPLAB though. Just copy the mcc18 folder to your Linux machine. The Makefile from 245 is also good to have. There's more information in this thread:
http://www.chiefdelphi.com/forums/sh...ad.php?t=36377