Are there other thumbnail scripts that do not require 'magic?
-G
It might be worth checking to see if the GD stuff is there and then looking for a GD version.
If they don't have GD then I second your proposal for a naff ISPs forum ;)
I do know there are scripts where you can have the thumbnails on a static HTML page and the script will link the thumbnail to the full sized image. In one particular case a background graphic is displayed full page without having to "do" the page, the script generates it. That requires nothing that isn't on all servers with Perl.
I went hunting for thumbnail scripts a few weeks ago and have some bookmarked, but I believe a lot of them did need GD. What exactly do you want the thumbnail script to do?