JKay - you are right with regards to the 01 model but I believe the OP's watch is an 03! Which in real life also has the same method, I believe, but in this case it appears to be a solid block of metal...
I think what needs to be done is you need to somehow unscrew / prise off the 'bezel' that holds the crystal in place - I don't think the case and bezel is a one-piece construction, I think the metal rings are put in afterwards, presumably with crystal already in place. Can you see a gap between the metal ring and the case? I think I can see one on the pic of the crown where it slightly overhangs the case?
Good luck if it is as I can't imagine it's going to be easy to get off! lol