To get a user's location from a click event you would need a few things.
Your menu item needs to of type click
"button":[ {
"type":"click", "name":"Get Location", "key":"location" }]Next you would need to setup a auto response for the keyword "location" that would return the user's location
You need to enable user location settings on admin.wechat.com first. Go to Service -> My Service. Under Advanced API enable "Obtain the user's location(Disabled)"
Look at the documentation here to get the user's location: http://admin.wechat.com/wiki/index.php?title=User_Location