An alternative is to use the remoteControl command (can't post links but search for it in bohemia's wiki) in combination with switchcamera , although when you stop the RC, the old "owner" (player) of the unit doesn't always seem to get the control back, has to reconnect (or go to the lobby and restart ) and there will be 2 units of the same name etc with one being controlled by AI .
To find out which unit you want to control , one way would be to do
{
if(name _x == "NameOfTarget")
targetunit =_x;
} foreach playableUnits;
obviously , replace NameOfTarget with the name of the player you want to troll.