pos_offset: This is an offset vector that moves the pov camera the specified amount away from the original camera position. Offset vectors like this one are usually written in this form: 'x y z'.
angle_offset: This offset vector changes the pitch, yaw, and roll of the view. It is usually written as 'p y r', but you can use a vector variable instead.
pos_reset_speed: This is the speed with which the camera returns to it's original position.
angle_reset_speed: This is the speed with which the camera returns to it's original angle.
Here's how SetPOVShake() is used in weap_bryar.cog:
SetPOVShake('0.0 -.003 0.0', '1.0 0.0 0.0', .05, 80.0);