Not a lot to say yet, but I want to get it started! Right now I have a Elm based tool from scantool.net It does not do what we want, but it does a lot, if you know how to access it. At this point, I do not know... Basicaly the cheap does baud rate, so the computer does not have to, and does basic header stuff. You can also do custom header, set the polling time, custom querries... But it is still an ODB2 system. However, couldn't a small dongle "trigger" the select monitor aspect as well? A very small componant to make a easy to get tool work for us.
Also, if you want to say, "Your wrong!" feel free, but you must offer a better solution if you do!