This is something I wrote a while ago. It's not much of a hack, and it's too simple and useful.
Drop a file or set of files on this app, and it will prompt you for a new type and creator. Because it doesn't use AppleEvents, it shouldn't be limited to 32K of file names like most of these programs (but it is limited by the amount of temp memory the Finder can allocate.)
Again, mea culpa. Shane Looker insists that Bill Gates is Satan's Love Child. Me, I dunno╔ the guy puts out apps that adopt Mac technology early on, and he sells a pile of them. He recently became the richest guy in the US, instead of just the richest guy in the US who needs a haircut. He must be doing something right.