The new unlock law just makes 3rd party unlocking legal again. There's a voluntary unlock agreement between FCC and the carrier consortium but that takes effect February 2015.As indicated no. Sprint does not unlock for domestic use - ever. And yes, I am aware of the new unlock law and so is Sprint. Sprint blames it on the manufacturers so that they have a technical out to deny you a domestic unlock even though the new unlock law applies to them.
That said, even if they did allow unlocking you still have the whole CDMA/GSM thing going on. I know the iPhone 6/6+ is a world phone though so that may not be an issue any more.
In any case - you can't.