I did this last summer. The condenser was the tougher part, but all of it is doable in a day of up and down under the car a lot. My nissens condenser came with a receiver drier already fitted... Thus leaving just 3 o-ring seals (iirc) all different sizes (iirc) for where the a/c pipes (hoses) conect:
1: high side compressor
2: low side compressor
3: at condenser
you can use saab part numbers, or just match carefully from a kit of o-rings (part numbers : 4757084 4756110 30541941
but double check)
if your condesner needs a receiver drier, that will be a 4th oring. (usually included with new part)
the key is not to pinch your o-ring seals, thus the lubrication helps.
if you have a vacuum pump you can draw a vacuum once youve tightened everything up and see if it holds overnight.
It took me about a day all said and done....the "pad" system seems to be easier to remove and install hoses and pipes than older connections in older systems i have repalced where there was more room for corrosion and thread striping...