xcode & Mountain Lion

I've created a new install of Lion from a Apple Store purchased USB Key, updated to Mountain Lion from the App Store, and I told the ML Installer NOT to include applications from the previous install of Lion. It created accounts based on Lion, but also attempted to install Xcode by linking to the LION volume.

Now, the app store sees xcode as "Installed" and won't install under ML.

Further adding to the insult, the previous installer won't run, and I find the now App Store version of xcode is not available as an installer.

Is my only option to do a "Clean Install" of Mountain Lion? Is this possible, or do I need go back to Lion, then upgrade again?

Thanks!