I have not found any information on how to do this, or even if it's possible at all.
http://msdn.microsoft.com/en-us/library/e13syb43
does not mention anything about building a portable class library, and
http://msdn.microsoft.com/en-us/library/gg597391.aspx
does not mention anything about a command line interface.
Has anyone else tried to do this and found a solution/found it to be impossible?