property scrollOffsetX

This property sets and gets the x scroll position within the current box. This value is only valid if the box overflowed in the x direction.

function SetScrollPos(boxId, x, y)
{
    var bx = scene.getBoxById(boxId);
    if (bx && bx.overflowed)
    {
        bx.scrollOffsetX = x;
        bx.scrollOffsetY = y;
    }
}