I used a product that I found while wandering around the electrical department of my local Lowes Home Improvement store. A link to a description can be found here
Its made from PVC with a self adhesive backing. I also pre-drilled and used 1/2-inch screws, 3 for each 5-foot section, just because I thought it would be more secure, although I wasn't really keen on putting holes into the skin. Actually, the short section in the back on top wasn't screwed in at all and hasn't come loose yet. We put on about 5,000 miles last year and the conduit is still as secure as the day I applied it.
One thing to keep in mind if you use this type of solution; When you have a straight run longer than 5-feet and you need to butt two pieces together, make sure the seams for the track and the cover are staggered.
Let me know if you have any other questions.