Is level hacking allowed on iw5m?, even though i just aim to be prestige 3?

No.

Unfortunately, no.

Of course, you can still get whatever title by using MassTumor's custom title program; and some cool camos, too- but the arbitrary numbers that define a level are locked.

 

24 hours of playtime aren't that long in the grand scheme of things; and the exact logical reason behind not allowing level boosters for this iteration of the game (they're allowed in IW4M) is as of yet to be found.

 

By the way, how far along in that goal are you?

No, you can't.