James,
1. move seat forward and remove seat rear 10mm bolt and washer with ratchet spanner, Photo 1
2. move seat fully rearward and remove forward 12mm bolt and washer, Photo 2
3. measure and insert noodles as necessary, can be cut with a hand saw. Use ties to hold in place if needed. Photo 3 and 4
4. refit seat, easier if rear bolts loosely fitted first then forward bolts, followed by tightening rear bolts.
Time to do, appx. 1 hour a side
Hope that helps. Note that my car had 10mm rear bolts and 12mm front bolts.
Garry