Sort of. You can make changes to the POI database without corrupting Maemo Mapper, but the image is not automatically refreshed, so you'll need to force a redraw in order to see visual POI changes. The easiest way to force a refresh is to zoom in or out. Not sure exactly what you mean, but if you just want to center the view on a certain location, you can use the "Go to" sub-menu of the "View" menu. If you really want to simulate GPS, you can use the command-line program "gpsfake", which is part of gpsd. This isn't trivial. Or, if you want to "simulate" having a "current location" in Maemo Mapper, so that you can use things like routing to a location from your "current location," then you can tap-and-hold on a location on the screen and use the "Set as GPS Location" menu item, in the "Tap Point" sub-menu.