You can do this by inserting the PSSE CD and clicking the "install" option when it pops up.
Follow the uninstallation process.
Reinstall PSSE
Reinsert the CD and again click "install"
Don't use your old Product Key! Use the new product key sent by email from your supplier. The product key in the CD wallet will only install the old features.
Wait when you get to the Dongle installation screen
Dongle Installation
When prompted, select to "modify" the existing dongle installation and then follow the prompts leaving the defaults. This should keep your existing dongle intact
Restart your computer
Before using the new PSSE installation. You should be good to go at this point.