Be prepared for a long, dirty job. Your knuckles will end up raw and your back will hurt for a couple of days. It's pretty straight forward, but everything will be in the way. I've done this 3 times, I don't look forward to doing it again. I recommend you stay away from the volvo kit, it is expensive because you pay for a slightly different evaporator coil, which I wouldn't install as it makes the job almost impossible. I ordered my parts from FCP Groton and if memory serves me right, to do the job right you will need:

2 rings for the compressor
2 rings for the condenser
2 rings for the receiver/dryer
3 rings for the expansion valve
A new expansion valve
A new receiver/drier
Flush fluid - about 1/2 gal
A set of gauges
A can of PAG oil
5 cans R134
Insulating tape
An air compressor, or better yet, a CO2 'blowgun'
A vacuum pump

You'll have to break the connections at the compressor, receiver and expansion valve, in the passenger's foot-well. Then you'll have to pour the flush fluid into the hose between the receiver and the expansion valve, the once between the compressor and the condenser, and the one between the compressor and the evaporator (this is the smaller of the two). Blow the stuff back out after a few minutes (I can't recommend those CO2 contraptions enough), install the new receiver, install the expansion valve, wrap it up with the insulation tape, install the new o-rings on every connection, but don't connect the compressor hoses yet. You'll have to remove the compressor, remove the drain plug on the back of it, pour some flushing fluid into one of the ports, and slowly turn the pulley by hand. Make sure you flush it well, put the drain plug back in, fill it up with PAG oil, replace the o-rings, and re-install it.

At this point, if you don't have a vacuum pump and gauges, you can take it to a shop and have them do the rest, they should give you a pretty reasonable price. Unless you replace the evaporator, which I wouldn't recommend, I think you have to under-fill the system by 20%. You may want to remove the passenger seat, working on the expansion valve is bad news... it's inaccessible and it's covered in a tar-like insulation that will ruin your day and your carpet if you're not careful.