Mapping for traktor keyboard (play button and turntable stop effect using transpose stretch effect)
Use the button V on generic keyboard as toggle for play/pause in target deck and sync deck(can be remove in traktor setting/ controller manager/ delete Sync On).
In order to get the stop turntable effect Hold on the button and on release deck target pause.  

Note: If use another button to play deck, press the button V twice in order to get the effect(on second press Hold it).