Yes, I have the vacuum pump and correct gauge set to draw a vacuum down to what is required. Sorry I wasn't clear about that in my first post. Following the shop manual, what I've done before is draw the vacuum with the pump for 15 minutes, let it sit for a while, and then start charging the high side with the engine off. Once the can is empty or it won't take any more, I shut off the high side and charge through the low side with the engine & a/c running until I get the right amount of 134a into the system.
I was able to find an o-ring set for my car at A-Z yesterday. I got some PAG 100 oil in a bottle also to lube the o-rings.
At this point, I think I'll just replace the o-rings on each side of the compressor discharge pipe. yarrgh - thanks for the suggestion about the dryer, unfortunately I'm running low on time and need this to be a quick job. Anything else I should quickly check though? Should I add more oil to the compressor? The shop manual only says to add oil when replacing components, but I wasn't sure if the oil can get lost through a bad o-ring.