My friend just did this on his RX7.
First he had a professional drive out and drain the system. From there it was pretty straight forward. He removed the pump from the engine, then started to remove a/c lines.
In the cab, he had to remove the glove box, and the large plastic a/c box thats behind it.
Once he opened the plastic box, he found the A/C core. removed that, reinstalled the box, plugged the holes in the fire wall and he was done.
Only weighs about 35 pounds on an RX7. I read that its close to 80 pounds on our car, but i find that extremely hard to beleive.
Corey