Drier/Receiver - pretty easy.
You'll see a can that looks like this:
http://www.ackits.com/partimages/accum/49123.jpg
Or this:
http://www.ackits.com/partimages/accum/49122.jpg
Ensure you have a generic GM O-Ring kit.
There's a side mounted pressure switch. It's attached to a standard schrader valve hookup. Unhook it from the wiring harness. Take a wrench, remove it from the schrader valve. Transfer it to the new unit. Use Nylog or GM spec high viscosity PAG oil to lubricate the threads.
As for the other parts - just unscrew the input/output sides of the drier. Replace O-Rings. Lubricate with Nylog or GM spec high viscosity PAG oil, reattach.
Ensure you add an additional 2 ounces of PAG oil to the system to replace the drier. Just add it to the compressor, you'll be fine that way.
As for the Orifice tube - I've never replaced one on an H2 yet. Sorry...