In my case, I just had to save repeatedly until it came out right. Sometimes it works on the first try, sometimes it takes a few tries. There isn't a whole lot to edit (easily) that you can't just buy. You can edit your money and drugs (ammo) and change your melee fight buff. Editing your weapon upgrades above 3 just makes them bug out and I haven't tried editing unlocks/completions.

Also, I haven't found any mention of the unlock cheats:
beatThisShit(gamechar); - finishes all missions on normal
unlockChicks(gamechar); - unlocks all chick options in sex store