how to put posable sim into a Build/buy blend file

I want to put the model of a sim into a file with my buy object, so I can mesh the item at a certain scale. I know how to export/import models from other files, but what file type should i make the sim so I can still pose it in the B/B file? Or do I have to pose the sim and then import the posed sim into my b/b file?

Thanks in advance,

Orange Researcher/cabaretchatnoir