Dan Mann had a truck with a manual transmission, but because of a herniated disc in his back, clutches and shifting weren't really a good option. So he got ahold of a 4-speed
4L80E automatic transmission, and with a bit of work (driveshaft shortened, crossmember added, height adjusted, etc) he got the transmission in. But without the transmission's computer.
Our intrepid hacker here bypassed the computer by wiring those three switches to the pinouts of the transmission/computer cable, and uses two of them to tell the transmission what gear to shift into. The other is used for the overdrive lockout, I believe, and he just lets the pressure level input default to maximim, which means harsher shifts, but who cares. His car has no interior clearly this is a man who can deal with a harsh shift.