Here are notes I made as I went along setting up my Zope site at iMeme. I've left them specific to my requirements, but that aspect is simple for you to ignore.
set up account
contact domain registrar to give DNS management of domain to iMeme (ns.imeme.net, ns2.imeme.net)
confirm with nslookup: any hostname in that domain resolves to IP provided by iMeme
any HTTP request for a hostname/root (http://webseitz.fluxent.com) takes me to Zope generic default page. (Note that Zope is running on port 8080, but request to standard port 80 is handled fine already.)
set up Access Rule to route different hostnames to different Zope folders.
approach options
this thread shows an approach that uses hard-coding of each hostname.
there's some iMeme documentation that shows a script that's more generic, mapping any x.fluxent.com to /x. So let's try this one. (Why don't they do this for every client automatically?)
go to /manage. Select pulldown Add a Script (Python). I called mine hostrule. No title or parameters. Copied in the iMeme script, hit Save Changes.
back to /manage root. Select Add a Site Access Rule. Type in hostrule as ruleid. Confirm.
requests for all hostnames still resolve to root, since no folders created.
make a top-level folder fluxent (decide to put all my stuff into a folder, with nothing else of mine at the root). Tweak the index_html. Now all requests for x.fluxent.com show that folder's index_html.
create subfolder webseitz within fluxent folder. Tweak its index_html. Now http://webseitz.fluxent.com shows that new index_html. All other hostnames within fluxent.com (including none at all) resolve to main fluxent folder's index_html.
note that to get /manage have to ask for just http://fluxent.com/manage (as opposed to www...)
virtualHostMonster: I thought I'd need to do something with this, but it's already working fine.