joe.domain1.ca?
We are hosting the boxes internally. Do I have to tell our Provider to setup come CNAMES or something like that to get this to work?
Yes. The zone record needs the subdomain added and pointing to your webserver. If you get tired of asking for sub domains of a particular domain, ask them to make a wildcard doamin of *.domain1.ca.
That is, if the zone file handler for your domains supports that heh. Depends on the software they use. I know for sure BIND9 supports it correctly, and so does DJBDNS. I've no experience with any others, and I would be skeptical of any windows-based dns server software, hehe chuckle.
Then on apache's side, just read up on that link posted by jstarkey. Its really a simple thing, as a subdomain website is basically another virtualhost directive (not something under another virtualhost).