Hi Matt,
If you install qmail, then vpopmail you just have to set up your qmail-pop3d with vchkpw. You can find all information about vpopmail installation in the README & INSTALL files. To set up you qmail-pop3d, in the qmail man pages or if you want to use IMAP & POP3 at the same time you may want to install courier-imap (which integrates directly to vpopmail authentication). Greetings !
