There is no CASC creator tool. You have to use hacky folder reading. Unless there is something to properly patch the client, it is useless for me. Someone could actually add support for MPQs back to it through things similar to TOM_RUS' WoWAddin.dll. I do not know how hard it is but I think you need to hook client's file loading functions and load MPQs with stormlib after CASC. I don't know if these functions are reversed or if it is possible at all but this would be nice.
If there is nothing to patch the client, there is no point to mod it. You can't ship loads of files to the end user right to the folder. Well, you can and pretty easily but it does not feel right.