Obfuscate Web Deployment Project-Output (bin) before Packaging into Web Setup Project

I have a solution that contains various projects. One of them is a Web Deployment Project and I need to secure the containing dll before it is packed into a Web Setup Project.

Unfortunantly that can′t be done via command line and I need the ability to tell the Web Setup project to just take the already compiled files from the Web Deployment Project without recompiling them during its own build process (because my modified dll′s are replaced).

How can I accomplish that?