You can use GetNamedNodeProperty(objRepeatingNodeParent, 'CTRL1', 1) to figure out which row is activated (substituting the appropriate dom node and ctrl_id into the parameters.
However, this does not cause an EVENT to take place. So you would have to likely use a timer in conjunction with this (might require the use of a task pane).
It would take some clever thinking and a bit of programming -- but I'm sure you'd be able to do this.