How to place marker with a click?

Getlocations does not have a function for that.

Markers represent locations which are associated with a content type using one of the modules that Getlocations supports, eg Getlocations Fields, Location CCK, GeoField or Geolocation. When content is created information can be provided so that a Latitude and Longitude can be determined, optionally along with address information. Once this information has been saved a marker can be displayed on a map.
I think you need to ask yourself, What are you trying to achieve?

OK, on the input map.
Please try the attached patch.

And would like to be able disable show default marker on node/add/* page. Place marker only after clicking or geocode.

I do recall customers using the old v2 Gmap finding it confusing that the marker was not visible so I will not implement that. The fewer clicks the better.

The click feature is useful and will be added to the next round of commits.