its a huge pain in the ass.
first... the seatbelt track has to be removed... that means removing the a/b-pillar trim... removing the whole interior side panels, and then removing the c-pillar trim.
once you've done that now you'll have to start unbolting the automatic seatbelt track and mechanism.
then on the b-pillar you'll see a small hole, that needs to be drilled out and a nut needs to be welded in place.
you'll also need to make a custom bracket for the new manual seat belt retractor mechanism.
then you'll need to make another bracket where the automatic lap belt retractor use to be... and that will be the anchor point to the chassis for the manual seat belts
after that... you'll need to weld nuts to hold the seat belt latch.
remove the seat belt box that is attached to the seat and remove the control unit in the passenger kick panel.
there's some pictures in this thread to show you...
http://g2ic.com/forums/showthread.php?t=194143
the carpet is also another issue but its not a huge deal.