To remove the seatbelts, you must first remove the Torx head bolts (with a torx #50 bit) for the metal loops (one near the speaker cover and one on the bottom of the doorframe). The bolt near the speaker has a plastic cover. You can pry the cover loose with a screwdriver (using the metal loop as a fulcrum).
Once you get those out, you then remove the B-pillar trim piece. To remove it, you must remove a philips head screw in the door jamb, and a couple of the rearmost screws on the trim piece that runs along the bottom of the door. Then you have to finnagle the B-pillar trim loose and slide it toward the front of the car. Remember to slide the seatbelts out of the trim piece.
Once the trim piece is out, you'll see a black box that the seatbelts go into. With a screwdriver, pry open the box and you'll see some mounting bolts inside. These bolts attach the black box to the frame. Once you remove those bolts, the entire seatbelt assembly should come out.
[This message has been edited by Blacktree (edited 09-25-2004).]