Robert,
Thanks for your expression of interest. Even if later, this is highly welcomed by those involved.
I can only second Héctor's statements: Going for a concerted backporting initiative for the current debian stable ("etch") *now* would not pay off in the mid run.
Waiting for lenny to become the stable distribution and then setting up backports of upcoming packages versions from unstable is certainly a valuable contribution.
In the meantime, you can use the current testing distribution for your server installations. All openacs|dotlrn dependencies are in there (by now). Backporting openacs|dotlrn packages themselves should be a relative ease.
As for the "package building environment", you can freely use the package sources for setting up your playing ground:
1. see https://openacs.org/xowiki/debian, follow the package links to the Debian Package Tracking System (PTS). There, links to the SVN repositories are given. You can use the Debian "svn-buildpackage" facilities to get the sources, mangle them, and build binaries and distribution packs therefrom.
2. the openacs|dotlrn packages are managed at http://cvs.openacs.org/cvs/installers/debian/. Here, go for "cvs-buildpackage". Once approved by the Debian Tcl/Tk Team, they will certainly move to the Debian SVN.
I am always happy to help out, once you decide to get started.
//stefan