All weapons, infinite ammo, medipacks
Turn Lara exactly North according to her compass, then enter the inventory screen. Highlight the "Small Medipack" selection and press L, Up, X, Up, R, Y, then exit the inventory screen. Note: An easy way to have Lara face exactly North is to have her hang from something facing North.

Infinite LaserSight ammunition
Have the crossbow or revolver combined with the LaserSight. Zoom in, hold L then press Start. While still holding L, select the pistols and press A. While still holding L, exit the pause screen. If you entered the code correctly, you will hear the sound of the pistols being drawn