Your issue is exactly why the official wheezy-backports repository exists. http://www.backports.org You could request a backport of 2.4.9 on their mailing list: https://lists.debian.org/debian-backports/
Though I or yourself would be much faster in creating the packages.
Edit: I would backport it against the version of libav in wheezy-backports, though. Plus the build-dependencies are hefty, so it's a big download if you have a slow Net connection.
Are you going to be developing against this library, or just have a program that requires it?
Edit: Opencv 2.4.9 needs this line added to the first section in the debian/control file
Code: Select all
X-Python-Version: 2.7