I wouldn't recommend doing a Rover 75 KV6 (2.0 or 2.5 V6) as a DIY job unless you are very experienced. It's a major job (book time is nearly eight hours) because there are three belts to change (two on one end, one on the other) and a lot of dismantling.. Pinpoint timing is also absolutely crucial, and this is one belt where you cannot improvise; you need the correct set of locking pins! If you still want to have a go, buy the Haynes manual which does cover the job, but I'd definitely read the full instriuctions befoere you start to take anything apart..
Peter Simpson (sold 50 Rover 75s on ebay!!), January 2008