Creating source packages?

[Jay Levitt]

I have a developer who lives in a rural area, with no broadband access.  
(OK, stop laughing.)  Worse, his 28.8K dialup ISP has an 8-hour max 
session time, so anything signifcantly large just can't be downloaded, 
period.

I want to send him a DVD-ROM of some large packages.  Ideally, I'd want 
them to look like just another source to MacPorts, so that the builds, 
updates, etc. all happen within MacPorts.  (Kinda like Fedora install 
CDs.)    And I want them to include all dependencies.

I've been able to create .mpkgs, but those are binary packages.  The 
guide mentions portpkgs, but doesn't say how to create them.  Neither 
does the man page. 

Is there any documentation on creating source packages?

Jay Levitt