Technically, the "Assembly" has no location as it is a logical concept - it
is really a grouping of modules (although most assemblies today are simply
single-module assemblies). Also, the IMetaDataImport API is directly related
to reading the meta data itself and the meta data is location independent.
Remember that .NET uses a structured "directory probe" approach to finding
the modules it needs based on the location of the EXE.

However, if you are using this API in conjunction with the profiling API,
you can get the location the module was loaded from via the
ICorProfilerInfo->GetModuleInfo() call (the name of the module is a full
path). This only works during runtime as that is the time when the module
location will be resolved.