To handle multiple accounts in Pine, you need to:
1] set the enable-incoming-folders feature
2] add the INBOXes at all your accounts to your incoming-folders list
3] add the mailstore specification for each of your IMAP accounts to your folder-collections list
I've written about this on my Power Pine page, which is here:
and my IMAP Service Providers page in this section:
Some of the information is specific to DreamHost.
Feedback is welcome!
Infinite Ink ~ http://www.ii.com
Deflexion & Reflexion ~ http://deflexion.com