Well I finally got deep enough into RIM's web site to find a phone number for their sales dept. I spoke to someone there who said that all I need to do is to purchase an S/MIME CAL, even just one. Apparently the email which includes the S/MIME CAL would also include a link to download the S/MIME Support Package. And that should be all I need.
Can anyone out there who has purchased S/MIME CALs confirm that?