Finding out where you got it would help. Some rebuilders include the gaskets and o-rings, but there'* alot more you should do in the process. Fuel injector o-rings and cleaning the MAF and TB for starters.
In the long run, you're going to need a supercharger outlet gasket, two yellow coolant o-rings, a throttle body gasket, and a fuel injector 0-ring kit.
Is the pulley still on the old supercharger? Did the new one come with one? Are they the same size? What do the rotors in the rebuilt supercharger look like? Shiny? Black? Dull gray?