Hi Paul
The following link has some information on collimation and how to do it.
http://legault.perso.sfr.fr/collim.html
I purchased some 'Bob's knobs' and have found them to be very simple to install and use. I have found that my SCT seems to keep its collimation for a long time. I usually only need to 'tweek-it' about every 12-months or so.