that lil shit that transforms into that giant one eyed monster?how do you kill it?

Which one..?? Do you mean the little prick Salazar...???

yes that bugger,ive tried everything?need help please?

If u mean salazar Shoot the giant snake s EYE until salazar appears then shoot him,he repeat the process.If u mean saddler Shoot his eye then stab him with a knife in eye until ada gives u rocket luncher.Now u have two options:
1.Use Special rocket luncher to kill him in an instant
2.Do the same process as before and u will kill him,later load the savegame that says Clear game and sell the special rocket luncher for 30.000 pts or pes whatever it says

I wouldent use the rocket, its a cheats weapon.

Get a Rocket Launcher before u fight him, shoot the BIG eye on the thing... repeat till Salazar is revealed. Equip rocket launcher, SAY CHEESE:D!!! and he's dead.