Came across this 'how to' in another forum, thought it might be usefull for people wanting to set up their chains to the proper tension, as a fair few people don't have their chains set up properly, thus shortening the lives of expensive chains and sprockets.
It will probably be of more use to people doing rebuilds, due to its suggestion of removing the rear shock to set it all up properly. Hope it can be of some use in any case.