Help: How to share virtual users between Postfix and CourierIMAP.

Hi, I'm using Postfix with SASL and CourierIMAP. I have multiple domains and I'm using virtual_mailbox+SASL's sasldb on Postfix and userdb for CourierIMAP... I found this stupid and if you want to add/delete/modify an user you have to do twice.

I considered pam_userdb but there is not much doc about it...

Any one knows a better way to have only one user db?