The protege SWRL tab is not available in Protege 4 versions, I have tried both protege 4.1 and protege 4.2. The axiome plugin mentioned to edit the SWRL rules in protege has bee
There is a Pellet plugin to support SWRL inference in Protege 4.x:
http://clarkparsia.com/pellet/protege/ (Reasoning can be started in Reasoner/Start reasoner after selecting Pellet)
This is a very complete tutorial on the integration of Protege 4.x and SWRL:
http://dior.ics.muni.cz/~makub/owl/