Shifting the eyepoint

Just wondering...In player.cc, there is a section at the bottom of ::getEyeTransform() that sets the eye transform. What I want to know is how to use that to shift the eye point 0.5 units to the left or right. That way, I'd be able to add a console function and key command so that I can allow the player to peek around a corner (I'll worry about the bounding box stuff later).