Movie Clip _x Direction and pause

programming flash
1

I have a movie clip (main_mc) moving from right to left, stopping on rollOver and continuing to move on rollOut like this:

onClipEvent (enterFrame)
{
_x+=(distance*speed);
if (_x > 0) _x=-641;
if (_x < -2197) _x=-688;
}

on(RollOver){
this.stopped = true
}
on(RollOut){
this.stopped = false
}
onClipEvent(enterFrame) {
if(!this.stopped){
speed = 2;
this._x -= speed;
}
}

I have 2 other separate movie clips (controlLeft_mc, and controlRight_mc) on the stage. How can I make these 2 movie clips control the x direction of the main_mc movie clip on rollOver?

Thanks