for now it's just a dump how I prepared some backport packages http://lists.debian.org/debian-backports/2010/03/msg00108.html
first of all, a series of links:
instructions about how to contribute: http://www.backports.org/dokuwiki/doku.php?id=contribute
packages already uploaded to bpo: http://www.backports.org/~formorer/changes/lenny-backports.html
packages in cpo NEW http://www.backports.org/debian/new.html
I used pbuilder to build the packages for bpo, so:
I created a separate basetgz for lenny-backports, where I added "deb http://www.backports.org/debian lenny-backports main" and also a local mirror for local bpo packges already built, needed to build the "target" package (remember to bindmount the local repo when build)
- each time you need to "force" a bpo package to be used, you need to update /etc/apt/preferences setting the priority of the package; with pbuilder, the easy way is to write a hook of category E: hooks/E01apt-preferences, adding the relevant information to it and then call pbuilder --update (sudo pbuilder --update --basetgz /var/cache/pbuilder/base-bpo50.tgz --hookdir /home/morph/deb/bpo/hooks/ --bindmounts "/home/morph/deb/bpo/repo/")
to prepare teh package, run dch --bpo, add yourself to Uploaders, debuild -us -uc -S, debdiff <old>.dsc <new>.dsc and then start the build (sudo pbuilder --build --debbuildopts "-v2.2.9-10" --basetgz /var/cache/pbuilder/base-bpo50.tgz --hookdir /home/morph/deb/bpo/hooks/ --bindmounts "/home/morph/deb/bpo/repo/" apache2_2.2.15-2~bpo50+1.dsc) - remember to pass -v<old version in bpo or stable> to --build)
- reiterate until done