I don't know of a free program but the Bluemusic3 from them is working quite okay. I use it since quite a while and it is worth the price in my opinion.
The only problem you will get is that it is interfering with the ms voice command! But there are workarounds, at least for me, since I use both.
So again, Bluemusic3 installs a driver that works and indeed routes the sound to a MONO Bluetooth Set! They have prooven my theory correct that its possible to do that and that SE and others decided not to to that "officially" (with a bluetooth profile) shows me just how much they suck.
«.·°·. Michael the Mage .·°·.»
<<<Of Peace, always!>>>>