This is totally un-necessary with this method. I did this on my 88 900T 3door, and it worked so well that Jacob used the same procedure when the seatbelts in his 89 900T 3door failed. I provided some minor assistance and took pictures. If you click on the 640 link, you will get a decent sized photo. If you click on the 1024 link you will get a very large detailed photo.
Instructions Remove the panels as shown in the photograph.
There are a handful of plastic twist screw things which hold these foam and plastic panels in place. The seatbelt motor is mounted behind this panel and has to be removed. This is the seatbelt motor right here. Flip the seat forward and unscrew the motor. There are wires under the seat which also need to be unplugged.