My mechanic changed mine a few years ago when I put in a Challenge pump. The engine does not have to come out and it was not a terrible job. Changing the steering rack is the real pain in the butt.
Engine does not need to come out, but definitely easier with a Spider with the engine lid removed. You will hate yourself for not changing it while the engine was out.
Sorry my bad, i mis read what you were asking. I thought you were talking about the Power steering rack , but now i re read it and you asked about the pump. Doh Stilll awkward though
Remove engine lid, place flat plywood, not a heaby one on top of the engine, lay flat on your belly, start working on it. You got two allen bolts and I think two 13mm bolts. It helps if the center piece of the engine covers are removed to access the hose clamps.