Port the location mapper from Feed Element Mapper.
Port tests for it.
I'm going to be frank: I am sceptical on including Location support in Feeds as the location mapper has caused a series of very confused and noisy threads on FeedAPI Mapper. I'm tired of accepting an initial patch and then somehow being responsible of keeping the functionality alive.
I can be persuaded. Alternatively, location mapper support could live in location module or in a separate location_feeds module.