Systems Management

I accidentally deployed the full add-in to some machines that had Outlook 2010 installed.  2010 is not supported and generates an error during the install.  I have realised my mistake, however I cannot deploy the correct add-in (Outlook HTTP Add-In) because it thinks the Full add-in is installed.  This is because although the original install failed (no Program Files entry etc) it did leave an entry under \HKEY_CLASSES_ROOT\Installer\Products.  I have confirmed that deleting this entry results in the HTTP Addin installing successfully.  The problem is how to get rid of that registry key on all my clients.  Obviously the preferred way would be to run the uninstaller, however this doesn't work because it fails when it finds Outlook 2010 is present (catch 22!).  Does anyone know a safe way to fix this without visiting each machine?  Although I know the product code that would be used in the msiexec uninstall, I believe the registry hive name it sits under (which is what needs deleting) is randomly generated.