Hi Nightstalker,
Very good article aoput colimation can be found here:
http://www.atmsite.org/contrib/Carli...lli.html#Step5
When I was doing mine recently, I was using a TV monitor to watch what is happening, through my digital camera - mounted co-axially on the eyepiece holder (without eyepiece, of course). This way it is relatively easy to centre the image of the primary mirror, you can see immediately the effect of every move.
The important part is to mark clearly the centre of the mirror with marker (this part of the mirror is obstructed by secondary anyway, so a mark is not a problem).
Good luck, Bojan