nah, i once tried to install the vista transformation pack and it screwed up all my skins so i couldnt do anything so i went into safemode and backed up and formatted.
You need the Nightly Tester Tools extension.
* Allows you to install incompatible extensions (experimental).
* Allows you to force the application to believe an extension is compatible with the current version and enable it. (Only works on recent builds of Firefox and Thunderbird, branch and trunk since 20/08/2005).
* and other stuff, but the above are the most important.