Firstly I have seen IEqualityComparer for anonymous type and the answers there do not answer my question, for the obvious reason that I need an IEqualityComparer no
This post may get what you want. Although for .NET 2.0 it also works for newer versions (see the bottom of this post for how to achieve this). In contrast to Jon Skeets solution we won´t use a factory-method like create. But this is only syntactic sugar I think.