fairly simple and generic instructions:
open rise of the tomb raider
open a save or what not, just get into the playing part of the game
open the cheat table
click the little computer on the top left and scroll down until you see ROTTR.exe, double click it.
a pop up will come up asking you if you want to keep current addresses, click yes.
cheat away my friends.
the cheats are pretty self explanatory.
note: this isn't mine, i just want to share. credits to STN.
have fun