This is a simple and straightforward mod. Prefab covers used to be available for the TJ, but I haven't seen any for the JK. My lab "puppy" is growing like a weed and will soon be relegated to the back bench, so I took matters into my own hands.
Needed: a roll of 1" wide painters tape, a few newspapers, 320 grit sandpaper, and one bottle of spray bedliner.
Step 1: remove the door frames and muckets from the body.
Step 2: tape the exterior side underneath the rails (this helps protect when sanding)
Step 3: two rounds of sanding. Wipe off excess with a wet paper towel and dry.
Step 4: prep prep prep!
Step 5: several light coats. I used one bottle for the entire job.
Step 6: allow adequate dry time and enjoy!