Subdomain Protection

Quick question:
If I set up S2member in www.example.com can I restrict access to www.forums.example.com - Looking to set up bbpress as a subdomain to example.com? Any help would be great!
Thanks in advance.
If I set up S2member in www.example.com can I restrict access to www.forums.example.com - Looking to set up bbpress as a subdomain to example.com? Any help would be great!
Thanks in advance.