MSBuild, include files based on a group of paths

Question

I'm trying to create a build script which would allow me to specify a list of paths to "module projects" that is included in a specific web site.

Hence, I have this layout:

customer folder
    |_MainProject
    |_ModuleProject1
    |_ModuleProject2

So, basically I want to be able to specify an ItemGroup that would contain ModuleProject1 and 2, and copy relevant files from it into the MainProject.

<ItemGroup>
  <CustomModule Include="ModuleProject1\*.csproj" />
  <CustomModule Include="ModuleProjec2\*.csproj" />
</ItemGroup>

In my main build script I then want to find out the paths to my satellite assemblies, as well as all dlls that reside inside the obj\Release*.dll folder of the project.

I already have item groups for the project file (.csproj), so basically I just want to add some more file references. But I can't figure out how I would do that. This is what I have today:

<Satellites Include="$(ReferencesFolder)\??\*.dll" />
<Satellites Include="$(SiteRoot)\bin\??\*.dll" />
<Satellites Include="%(CustomModule.RelativeDir)obj\$(Configuration)\??\*.dll" />

How would I go about making the last line work based on the facts that I have?

When doing this:

<Message Text="%(CustomModule.RelativeDir)obj\$(Configuration)\??\*.dll" />

It outputs this:

ModuleProject1\obj\Release\??\*.dll
ModuleProject2\obj\Release\??\*.dll

And if anyone has some links to the fundamentals of MSBuild with good examples, I would really appreciate it. I always end up at msdn with some really cryptic examples that doesn't really explain a lot.

EDIT: I revised my plan and almost have it working, however the include doesn't really work as I expect it to. Nothing is included, but there are files mathing the path.

If I manually add this:

<Satellites Include="ModuleProject1\obj\Release\??\*.dll" />

It is actually included in the "Satellites" item group.