Can Anybody Recommend A Script/Client

Hi, I am currently running afterlogic on a subdomain of my main site so that users can access webmail. However my problem is they cannot create a webmail account through this. I must log in to cpanel, set up the account, then it works. So i was curious if anybody knew off hand of any way to allow users to fill in a simple form and thus register a webmail account. I'm looking for a php script or even a client that I can edit the settings file on to only have the register page, this way I can just throw a link up to that page and they can create an account there.

Any help would be awesome,

Thanks!

Edit: A vbulletin plugin would work too. I've been trying to figure this out for so long and really don't want to create my own script since I'm inexperienced with both cpanel api and email servers in general.