When I get to that point, I plan on painting the hinges installed on the car with a touch up gun. It'll be one of the first things painted in the trunk. Once flashed, change the angle and get the other remaining areas that weren't exposed.
Anyone looking upside down inside in my trunk to see if it's painted there might lose their head.
If you insist on taking them off and painting separately, you can buy the clips from R/T Specialties. Dave at Roseville may even have them.
The clips are located up under the rain gutter channels on the sides of the quarter panel. They are only good for one installation. When you take them off, they really aren't worth re using a second time.
http://www.rtspecialties.net/proddetail.asp?prod=1004217