Unable to Reinstall Upgrade to CS5.5 (lost DVD) with Installer as Qualifying Product (CS3) isn't included as menu option. I have the serial numbers for both versions.

I lost my CS5.5 DVD and the upgrade with the Installer doesn't work as only CS4 is listed as a qualifying product in the pull-down menu.  I have serial numbers for both CS3 and CS5.5.  In the interim, I've installed a trial version of CS5.5, but how can I add my serial number for CS5.5? Thanks.