Adding ground cars to traffic ?

Hey guys,Just curious. Just finished reading through the FSX SDK SP1 and cannot see how to install a new custom car to ground highway traffic. I see that they are listed in the LWcfg.spb file by their GUID's, (which means of course you cannot bring in anything without a GUID into living world works, which is ok I guess). But how on earth do you edit the Living World config file? (That is the LWcfg.spb file).I opened this in Notepad and its similar to a MDL file in code.Any idea's on how to enter a new car into the highway traffic?Bill