Once you put your molded carpet in don't be in a hurry to trim it and put the seats in. I put mine in and walked on it for a week while I did other interior work, that way there is no worry of having it pull out of the sill plates. Once I was ready to do the belts and seat I took an old soldering iron and ran it through the holes from under the car, not just the tip but the body of the iron. A couple I could only get the tip through from the bottom but opened them up from the top. Locating console brackets take a little more work.
Alan