Reply to VCI 400 + Denon 3900 with Traktor?

Trying to find the best way to set these up so that I can use the mixer controls of the VCI 400 with 2 3900's for deck C and D for scratching and juggling. Is this possible with Traktor without buying an external soundcard? I know that I could use them through the stand alone function, but would prefer it through Traktor. Would midi mode from the cdjs to Traktor, and then out through the VCI 400 work? I really don't want to buy another piece of gear, and suppose I could just go with the 2900s, but I really want the spinning platter, as I miss the feel of my technics.