Hi. I ordered a TIM sim from intouch for my Sicily trip and they sent me a Wind sim instead..........

so I had to call them and tell them to send me the right one that I ordered. They said that they don't sell TIMs (even though they have it listed on their website under their Italian sim) anymore based on the fact that they have problems with registration..........I'd rather risk it because everyone else i know will have TIM and I'll feel more comfortable coveragewise. Anyway, I don't mind stopping into a store to register it correctly or whatever, but what do I need to do to insure that everything goes smoothly? The guy on the phone offered to send me my correct sim anyway with some paperwork for registration but said I'd be on my own from there and would more than likely have to stop i a store to get it to work.
I have registered for the fiscale thingy and I'll have my passport and whatnot, but what else will I need to do? Would I be able to activate it without problem once I fly into Italy? Can the sim be registered online? Would I be able to fax documentation to TIM to make sure the card will work when I arrive? Thanks.
Edit:fyi, I ended up buying a quadband phone, so I'm otherwise all set.
Thanks.