Very easy once the wheels are off. All 3.2s have a 2 piston open saddle caliper design which is similar to the later (and current) 4 piston aluminium calipers - only smaller and made of steel. This allows pads to be simply dropped in or out, very quickly and easily. The later 3.2s have a very simple system where the pads are held in by two pins alone. Earlier cars have some stainless hardware on top of this but the two pins idea is still the basic part of it. Once you have the pins and hardware out of the way (pliers and a small punch and hammer are all you need), you simply lift the old pads out. They may need a little wiggle or gentle persuasion to get them out. To get the new thicker pads in you will need to push each piston back into its bore slightly. The piston is surrounded by a dust/debri seal, so if you use a screwdriver or other metal tool to lever the piston back, just be a little careful not to catch and rip the seal. The new pad drops straight in, the pins secure it and replace the other retaining hardware (if relevant).
If you just want OE pads then your OPC probably sells these almost as cheaply as anywhere. They are probably no more than £40 per axle (cheap as chips in Porsche terms) and do an adequate job of stopping you with minimum fuss, noise, dust, last well and have adequate operating temp ceilings. If you want a track pad then that is a different story.
HTH
Richard
