Based on that, I'd then edit it like this:
mob
var
controllingsomeone=0
beingcontrolled=0
tmp/mob/cm//controlled mob
//after jutsu is done.
cm=whatevermobisaffected
controllingsomeone=1
//---
whatevermobisaffected.beingcontrolled=1
//------
mob
Move()
if(src.beingcontrolled==1)
//set macro to something blank where they have no controls. switch off all of their movements somehow.
else if(controllingsomeone==1)
cm.Move(get_step(cm,src.dir))//move the person you are controlling instead of yourself..
else
..()//normal movement
Personally I'd be very careful with this type of skill. It can quickly OP a person if it doesn't have balanced limitations.
Also, be sure to note that if you change your mob to another players, it'll disconnect their client. So you wouldn't want to allow a method like this to be used ON a player.