Id say most mechanics should be able to manage it. Though if its a dealer selling it I would be asking them to do it to secure sale

Heres whats involved
http://www.alfaworkshop.co.uk/cambelt_change_16_18.shtml

If your mechanic doesnt have the correct tools etc there are plenty of Alfa specialists that will do the work.

Cant go wrong with Jonny Cargo just outside Lisburn

cheers
Ian