I have that same sander and was supplied an odd shaped tool that's designed to help you hold the clip open when changing belts. I've never used it, though, I usually just hold the clip open with my finger. It's a tight fit, but I have small hands, so it's doable.

When I'm changing the belt, I usually start with the right end first. I trim the end of the paper, then stick it into the clip. Pull it tight, and then start wrapping the paper around the drum, keeping it tight and aligned properly. When you get to the end, cut the paper a little longer than needed, maybe 2" longer. Then make a mark on the paper where the drum ends, so you'll know where to start trimming. At the clipped end, make another mark, roughly an inch away from the edge, so you're forming the "tab" that will fit into the clip. Now test fit the paper onto the drum. It will probably overhang the drum a bit... you'll have to trim it again. Keep trimming it until it fits nicely, and make sure that your "tab" will fit into the clip. I think it needs to be about 3/4" wide at the tip end.

Make sure the belt is wrapped properly, and then stick that last tab end into the clip. When you release it, it pulls the paper tight.

I usually sand a piece of wood through the drum a few times, the paper will stretch a bit. Re-tighten it and you should be fine.

BTW - I recently met a fellow woodworker who swears by the purple abrasive paper, I think it's made by 3M. He said it's more expensive, but lasts 10 times longer. The next time I buy paper, I'll probably try that stuff, as I hate changing the paper on these sanders. It's a pain!

Hope this helps.

Here is a link that might be useful: My woodworking blog