So far google api has been integrated and tested to support the address map feature, I am not sure if there is any other way, however you can trying use action sets to handle events which can call an activity to invoke your REST API.
@baigh. thanks for the response. The invocation of REST API seems reasonable. In terms of display of images (aka map), would the pxAddressMap still be usable or is there something better to use? Does Pega validate the Google Key ? or is it anticipated that the service provider (in this case, Google Maps) would validate the received "key"?