Adding Maps to iWeb (using something other than address...geocoding?)

Hi. I am trying to find a way to make the google maps widget find a location based on something other than the address. They can't seem to see certain addresses, say in Australia, and it's just altogether unreliable for me as many of the addresses I want to use just don't compute in the widget. I am trying to post maps of certain vineyard blocks that may or may not have a physical address.

Is there a way to place a marker in the map based on something else like latitude or longitude, gps coordinates, or even saved locations in my google maps account? It would have been very easy for Apple to make this function a little bit better (such as letting you use saved locations). There is no documentation by Apple that tells me how to do this that I have found.

Any help is greatly appreciated.