HTTPS filtering is not supported on the CSC AFAIK; the guide reads:
"Traffic moving via HTTPS cannot be scanned for viruses and other threats by the CSC SSM software."
http://ciscosystems.com/en/US/docs/security/csc/csc63/administration/guide/csc4.html
Also I think MPF (regex matching) does not support HTTPS either, as stated here:
http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a0080940c5a.shtml
I think your only option would be to integrate your firewall with websense or N2H2.
If the website IPs are static (and less is number), you may do a lookup for them and block 443 access to them using access-lists.
Please rate if helpful.
Regards
Farrukh