ConfigureUnDouble installation help

I am having trouble installing the ConfigureUnDouble tool. I followed all the directions, at least I though i did, and it keeps giving me this error message: "Falure initializing gacutil". I'm not sure if the gacutil.exe is failing or if the dll is not getting created properly. Can anyone help with this?

GACUTIL is a utility that comes as part of the .NET framework. If you open the Visual Studio 2005 Command Prompt and type GACUTIL /?, you should see a list of command line switches. If you don't, something is wrong with your .NET / Visual Studio install.