I believe the four screws do adjust the front mirror alignment. I have not done this personally. Theoretically, you would need to simultaneously back off one and tighten the other that is 180 degrees from the one you loosened. Perhaps someone with actual experience can provide advice.
Here is a video that explains how optics on a laser are normally aligned:
http://www.youtube.com/watch?v=U8yLS4K8nM4
The issue for this situation is you are not able to remove the front mirror to set up the alignment laser through the center axis of the bore.
If you attempt to adjust the front mirror, use two insulated hex keys. You would have to align by trial and error.