In case you happen to be needing to do host headers with a wildcard SSL Certificate, here is the article from Microsoft on how to do it in IIS 6:
The basic command line call is:
cscript.exe adsutil.vbs set /w3svc/<site identifier>/SecureBindings ":443:<host header>"
Where <site identifier> is the numeric identifier displayed in IIS, and <host header> is the header you’re trying to capture for the given site.
Also for reference, the full path to:
cscript.exe is c:\windows\cscript.exe
adsutil.vbs is c:\inetpub\adminscripts\adsutil.vbs