I did one of mine last year, if it is the one in the photo linked to above. It was perfectly straight forward and the part I used - the dust cover, was a standard off the shelf item (not Rover specific) costing a few pence. The only special tool needed (possibly), is a ball joint splitter, but I think mine cam apart without. It bit tricky to get the cover in place, but it can be done with just the basic tools if you are careful. They are held in place with a spring wire, a bit like a very thin version of a key ring.

I went for it and ordered the rimmers part so come next weekend there should be some swearing from under my car....

I was assuming it was the large central ball joint that attaches to the hub.

Rimmer's boot kit points to the front subframe mounting. Is that the one that's split?

TC