You need at least three values to describe an orientation in three dimensional space.

For arbitrary values you can't convert pan+roll to pan+tilt.

But for just looking to the right direction the pan value alone should be enough. Or what do you mean with "facing right"? Do you have any constraints for your angles? Maybe you could also change the orientation of a model in MED so you could rotate it in your game via pan+tilt instead of pan+roll.