You may be able to do this with the standard OS... not tested this in
particular, but of you connect both headsets, go to the BT Settings
and long press on the BT headset. You should then get an option to
select which channels you want the headset to pick up, ie media and/or
phone audio. If you select only phone, then media should playback
through the wired headset and calls should route to the BT headset.