need some cheat codes for Contra 4

Contra 4 is hard, and i need some cheat code. I fuond some on the gamefaqs but i don't know how to use because the gamefaqs explaination to use them is hard to understand.

The gamefaqs cheats? I could use the weapons modification cheat but not the 30 lives cheat. Maybe that's a fake cheat?

there was a cheat.dat that was regularly updated to include the newest games, anyone know what happened to it?