Hi Vikram,
You can disconnect the ESRI Zoom To function like this:
dojo.disconnect(map.infoWindow._eventConnections[4]);
This assume your var map = esri.Map(). The the fifth element in the _eventConnections array is the zoom to event.
Then you can attach your own events to the Zoom To with jQuery or dojo:
// Add custom zoom To
$('.action.zoomTo').click(function () { alert('First!'); });
$('.action.zoomTo').click(function () { alert('Second!'); });
It appears that the new connection can only be made after the an InfoTemplate is instantiated.
Best Regards,
Manish