If you're making belt loops as floating geometry, surely it's much much easier and more accurate to project all the belt loops as geometry, rather than manually doing anything in photoshop? instance the geometry, space it along a spline if you need a lot of them, use advance painter script if you're using max to place them…
Chiming in to say get the Advanced Painter script. http://www.scriptspot.com/3ds-max/advanced-painter It works in Max 9, I use it at work all the time. It lets you select a piece of geometry as a "brush" and then paint it onto another piece of geometry - so now those 20 screws you wanted to put around are all properly…