How to fill A/C?

[deliriousga]

I had to replace the air box and drier in the A/C system when it blew up on our 2000 Boxster so now I need to refill the system. Does anyone know if I have to take it to a shop to do this or can I just get the R134a and fill it up myself? (Not sure if it will draw in with an empty compressor.) When I call around to the quick-lube/tire shops that do A/C, they will not do it on a Porsche and I can't lose the car for a day or two to take it to a mechanic right now, but we're in the upper 80s in GA and it's hot for the wife in traffic.

Thanks!