Steering and suspension replace steering rack boot
Count threads showing at tie rod end, crack the lock nut against the tie rod end, then remove the split pin if present(original but nylocks are ok) and remove the tie rod end nut and shock, or ball joint splitter , the tie rod end out of the upright, then hold the tie rod on it's flats and unscrew tie rod end from the tie rod, slip the remains of the old boot off the end, and as they say fitting is the reverse. It is good practice to have the steering alignment checked when such work has been carried out, and lots of copperslip on all the threads is good so any adjustments needed can easily be made
I would just add before cracking off the lock nut draw a line with engineers chalk (actually more waxy than chalky) across the threads and likewise track rod end (tipex is another option), count off the turns (screwing off the track rod end) this way when reassembling you will be able to get the track rod end in exactly the same position as it came off and as long as the tyres were wearing evenly before there shouldn't be any need to adjust the tracking afterwards. Of course the original straps are best to retain the new gaitors but locking wire is a good second, cable ties are a poor third option (if you can't retain the gaitors with either of the first two methods) copper wire out of a piece of 2.5 twin and earth cable makes pretty good locking wire (two full turns around the gaitor)
I did this job a couple of weeks ago and also have a LHD with power steering. Did it exactly as Aidan says with the steering rack in place.
Found the hardest part was getting the rubber over the end of the steering rack (the end with the bigger hole) as it is difficult to get your hands to the back side of the boot next to the transverse beam. After a few attempts and much swearing I managed it.... It helped to soak it in boiling water to soften it (making sure the inside is as dry as possible before it goes on). Not sure this is recommended but makes it a whole lot easier
it's not easy on a ps van, in fact it's not that easy on any van insitu - it's easier to remove a manual rack and do it on the bench, but removing the ps rack is definately harder than the manual one as you'll have to break into the hydraulics and change the fluid (not a bad idea anyway and do the filter too )