Can I point a sub domain at a cgi script?
A subdomain in DNS can only point to an IP. A full URL (ie. a script) is above the level of DNS. DNS only understands
IP’s and domain names. Not full URLs.
You can use the 403 redirect option to have the webserver forward the subdomain request to the URL.
Another approach is to point the subdomain to a sub-directory in the control panel and then have that sub-directory’s index page immediately redirect to your cgi script. You could also use .htaccess to make the filename for your script be one of the index pages.