Download tenon's iTools from versiontracker.com... I havent used it yet, but it supposedly provides a GUI for doing things such as setting up virtual hosts, without you having to know a damn thing about it.

I think you only get to use it for 2 hours or something before it expires.. but if you get everything done that you need to in that time, its no biggy. If you need more VH's later, you can just go into httpd.conf and copy and paste the stuff.
I think there might be a thread or two in these OSX forums about it as well, I remember reading thru the steps somewhere.