Hi,
They made a special input type called audiencePicker for AAM integration that can be (ab)used.
Look at the way nms:validatePicker.jssp works, it's several specially named hidden <textarea/>'s and window.location being set to return type, either xtk:segmentPost or xtk:closePost.
NB this is undocumented and looks hacked together, so may be refactored in a future release in a breaking change to your code.
Thanks,
-Jon