I didn't use any clips or adhesive or anything like that. I just cut the plastic big enough to sit in the grooves. Bend it a little to snap it in place and it stays. We don't take it out, but it could easily be taken out and put back in. No modifications to the door or anything. Been that way now for almost 2 years.
1999 Silverado 1500 ECSB 4x4 5.3/3.73s
2009 Jayco 32BHDS