Rich
Tar paper glued itself to the painted floor, then jute underlay laid onto floor (unglued with black latex side up) held in position by the female base of the carpet snaps and a black painted steel strip (slightly larger than the runners / wood strips).
A hard wood seat runner packer (also oiled or painted black)went on top of the metal plate with the seat runner sitting on top of this. The seat runner studs therefore went thru (from top) the wood packer / steel plate / jute / tar paper / floor.

TH---

The unbound karvel carpet had slots cut out for the runners and was held in place with the other male half of the snap.This is the correct way to do it.---Keoke
If you fail to incorporate the slots and your carpet gets wet you gonna have a devil of a time getting it out to dry everthing up OK.--Still Keoke :laugh:
Therefore the metal plate helped to compress the jute and the wood packer gave enough clearance over the carpet.
Some people dont cut the carpet but again sandwich it under the runners (believing it will give a cleaner look, which it doesnt if done properly), and I think you will find the studs are not really long enough.
cheers Andy
and as Mike noted you can get the carpets out if trimmed around the runners, maybe not the jute but it can allow it to dry, but then again most cars have a more pampered life now!