How to specify a an IMAP port to use?

[Kyle Jensen]

Hi! 

I'm playing with the Horde's IMP, which depends
on imap-uw.  However, I'd like to use courier IMAP
instead so that I may use Maildir-formatted mailboxes.

Is there any way to "tell" the ports system that this
is the IMAP variety I want?

(However, in this case, I think IMP will need imap-uw
anyway because it needs to build against the c-client
libraries....nonetheless...)

Thanks so much!
kyle