Assembly.Location in PCL on Phone/WinRT

To determine the given build date for certain assemblies I have a method taking in an Assembly object. From there on it calculates the build DateTime (similar to this method: RetrieveLinkerTimestamp()).

I'm writing this in a PCL project, targetting Phone & WinRT as well. I see that the "Location" property is not available on "Assembly" objects when activating those PCL targets. Is there a workaround to get the physical "assembly" in memory, so I can read the physical bits - or is it (e.g. due to recompilation/optimization in the store) no longer valid? Any workarounds are welcome as well.