Well, it seems this is my answer to that question. However, instead of "web[WEBID]_", is there a variable like "[DOMAIN]" or "[SITE_NAME]", so users can't see how many other users I've already created, and each login seems more specific to the particular domain?
Please have a look at the FAQ: http://www.howtoforge.com/faq/index.php?action=artikel&cat=14&id=47&artlang=en&