I have followed underdark's clear and concise "how to" to get osm2po running. The web service is a great little tool for inspecting the data. Is there a way to restart the service using an existing run after closing the command prompt (i.e. stopping the service)?
I'm guessing there is a way to do this without having to convert all the OSM data a second time. However, the documentation is in German so I can't tell.