You cannot add multi-velocity samples into SSD4, you can only import 1 straight sample or use the SSD samples. Personally, I don't use joey's drum samples because I don't think they sound good or useable. If I had to mix SSD room with joey's samples I'd just bounce the SSD room and OH tracks separately from the direct mic tracks. Make sure your kontakt 3 instance that you have your SSD samples in is set to multi-channel out mode, that way you can set up aux tracks and bounce the channels individually, i.e. one for the direct mics and one for the SSD room itself etc.