We use DNN for our intranet.
Since many functionality are duplicated (I pretty much started lately taking over from a contractor that left) I started my own class library where I place "non dnn specific" functionality, to be shared among all future modules.

Today I created a package for the first module that uses this library (keep in mind the lib will be an ongoing thing, but I hope to keep things in check by having unit test of over 95% code coverage)

However I got a bit lost about how to make sure this dll get included in the package.
I managed to make it work by manually copying the dll to the dnn installation's bin directory and including the dependency in my .dnn file (think it was something like <dependencies>MyCompany.MyLib</dependencies> )

What would be the correct way to have this dll included in all module installation packages?

For what it matter, each module, while under development is in a solution that includes the module, the class library (since I add stuff to it on a continuous basis) and a test project (msunit) that ensure changes to the library does not break existing functionality.