Ok got this running with DarkXL and I am enjoying it very much. I can get some of the cheats to work via the console(~) key, but cannot get invincibility code to work with DarkXL. Does anyone know how to do this ? Thank you.

I don't know if it's the same with DarkXL but in the regular DOS version you just type the codes in - no console required. The invincibility code is IAMLAME. Try just typing it while you play.