By texture panning do you mean a sort of texture scrolling/moving texture? There are texture scrolling commands you can put in your VMT but I can't remember what they are. I'll have to look it up again.
Try looking for materials that use scrolling overlays like those combine screens you see throughout HL2. You can look at the VMT without having to extract it. There should be something in the "Proxies" section about texture scrolling if the material uses it. I don't now much about it myself but I'm going to look into it. There are too many parametres for me remember.
Hope it helps and is what you're looking for.
EDIT: OK, the link is forbidden or something so I guess you'll have to do a Google search.