For each of the markers in wagmp_map_<mapnum>.php, you will want to find this code:
GEvent.addListener(marker_0, 'click', function() {
marker_0.openInfoWindowHtml(address_0.infowindowtext);
});
and change the click to mouseover, so it looks like this:
GEvent.addListener(marker_0, 'mouseover', function() {
marker_0.openInfoWindowHtml(address_0.infowindowtext);
});
After that, you will want to add another event listener to close the window on mouseout (if that is the functionality you want).
GEvent.addListener(marker_0, 'mouseout', function() {
marker_0.closeInfoWindow();
});
To prevent the info window from popping up on default, you will have to find the code similar to this for each marker and remove it:
if('address_0' == 'address_0')
marker_0.openInfoWindowHtml(address_0.infowindowtext);