I'm writing an application that relies on a closed-source (but free-as-in-beer available) library.  I'm currently making a Debian repository to host it, and need a way to depend on that library, so I want to make a package that downloads the archive from a third party and installs it.  I'm not sure how to do the install such that it will uninstall nicely.  Any ideas for how to do this such that it integrates nicely into apt?
Debian package to install closed-source
debian;packaging