Each manufacturer has their own software and connector cables for the interface. It requires using hyper terminal and the protocol in the ports and the communications software will have to be tweaked on the laptop or what ever you are using to hook up.
The software is expensive and the connector cables run about $150.00 on up. They just don't sell the software to anyone from what I can tell. I've done a few trucks and each OEM is different to a certain degree.