try using /set engageplayerpos 0,0,0,0,0,0 and /set engagepalyerrot 0,0,0,0,0,0

There are 6 digits for each, just play around with each one, start a new match (ctrl+n) each time to see what it changed and yeah.. there are 3 0's for uke and 3 for tori for each :P