Yes, open your Project64.cht(in your PJ64 main directory) & add the wanted cheats under the appropriated games, follow the format which is already there.
i.e.
Adjust whats in the red zone:
Cheat6="All Stages\Infinite\Pulse Ammo",81074204 2400
Cheat7="All Stages\Infinite\Flame Ammo",81073720 2400
Cheat8="All Stages\Infinite\Seeker Ammo",81073A94 2400
So,
1- Change the numbers after cheat(1, 2, 3, 4, 5, etc...).
2- Enter the names of the cheats(in other words, the names which is going to appear in the cheat box) if you want to make a cheat groupe, put some slash in between the name like i did in blue. So in all stages get infinite weapons.
3- Enter the GS/AR codes.
Save & play, don't forget to create a back-up before editing Project64.cht.
Good Luck & Have Fun!