To install 32-bit drivers on a 64-bit Windows Server 2008 print server is a bit complicated (as I found out). To install the 32 bit drivers, you must do so from a 32-bit client.
1. From the 32-bit client you will add the printer. You will get a message about the driver not being available on the server and you will be given the chance to install one.
2. Install the appropriate 32-bit driver. Note: the 32-bit driver must match the name of the 64-bit (i.e. if the driver installed for the HP LJ 3220 printer on the Printer Server is an HP LJ3200 driver, then the 32-bit driver must also be the HP LJ3200 driver, even if there is a specific 32-bit HP LJ3220 driver. The server and client drivers must be the same!)
3. Open the printer properties on the client system.
4. Navigate to the sharing tab.
5. Add additional Drivers.
6. Select the appropriate environments and versions (XP, 2000, Windows 98).
7. Select OK and provide a location for the driver (if necessary).
8. Viola! The printer drivers will be installed on the server.
A big thank-you to JC Warner who researched this and sent it over to me!