Extend file based resource manager

Question

I want to store my resources in a different file format than NET's  .resources (in particular, .po), so I wrote a custom resource set with a custom resource reader to retrieve them. I created a ResourceManager using the CreateFileBasedResourceManager static method which creates a new instance of the manager that retrieves resource sets from files in a specific dir, using the specified resource set (the custom one I wrote in my case), using Name.culture.resources filenames.

However, I would like to change the filename convention. I noticed there is an overridable GetResourceFileName method for precisely that purpose. But using reflector I noticed that the constructor used by CreateFileBasedResourceManager is private, and it is impossible to set the "use files instead of assemblies" flag otherwise.

Is there any way to go around this, without needing to reimplement the whole InternalGetResourceSet method?

Thanks a lot!