First of all I am not sure if this is a right approach or not. If you open the jquery.vmap.js
plugin file, check out this code:
if (e.type == 'mouseover') {
jQuery(params.container).trigger(regionMouseOverEvent, [code, mapData.pathes[code].name]);
Change the code of the following line to:
jQuery(params.container).trigger(regionMouseOverEvent, [e, code, mapData.pathes[code].name]);
This event e
is passed as a parameter to the function in the plugin. And in your call back function add one more parameter
onRegionOver:function(event,e,code,region){
alert(e.pageX,"_",e.pageY);
}
This worked for me...Hope this Helps for you