Cant find anything definitive on this! The front seems pretty obvious, keep the two threaded adjusters at the top locked so you're not adjusting the pre-load, loosen the lower and twist the whole unit to the desired height? The rears are in two pieces, do you adjust the two threaded adjusters on the spring, or do you keep them locked and twist the shock unit to lower/raise the overall ride height? I'm concerned that adjusting the spring perch will alter the pre-load?
Actually looking again, I can't see how the rear is pre-loaded and adjusting the shocks would just effectively shorten the travel?