I had this system years ago. The boost sensor was a 3 bar MAP sensor. Power for the sensor came from the TPS (a set of plugs intercepted the 5V power and ground). The signal was run through the temp sensor line (temp sensor was unplugged). The computer used a default value for temp.
The scan rate was way too slow and there was no tuning capability, but it was one of the best systems at the time. I’d look at some current systems like powerlogger/turbo tweak 6.0, translator products, Fast XFI, Bigstuff3, etc