Hi! mate,
undo the battery 10 mins before so the airbag doesn't go off when you unclip the orange wires under the seat from the pretensioners. Undo the 4 torx that hold the seat frame in the car and now unclip the orange wires, remove the plastic trim bits(couple of torx again), remove the seatbelt pretensioners, flip seat upside down and there are 4 more torx to undo that hold the frame to the seat. I had to move the runners a little to access them and if I remember they were color coded with a dob of paint on each torx head(Yellow and pink so take note which are at the front of the seat and which are at the rear).
Just Reverse once you have changed the runners overs. Hope this helps, Rez.