Allan if you use method C as described in the "sky and telescope" article, using a sight tube (which is what I've been pushing I guess) you dont have to worry. Just centre your spider and secondary mirror, use a sight tube to set up your secondary(then the cheshire to do primary) and you are done. I get good collimation with that method. The amount of tilt introduced is negligable and undetectable as far as I know. Though if you want to go for method B thats fine too. Let us know how you get on.
Cheers mate, Richard
