Getting an export from an MEF container given only a Type instance

I have a scenario where I have to get an export from my CompositionContainer instance but I only have a Type to work with; I don't know the type at compile time, hence I can't retrieve the exported object in the normal generic way.

Normally you would do this:

_container.GetExportedObject<IMyType>();

But in my case, I have this:

Type someType = ... ;
_container.HowDoIGetTheExport(someType);

Any ideas?