I got the gauges off ebay and slipped them over, but I forgot to put the needle stops in and started the car. Of course this messed up where the needles sit.
Check this
link
The fuel and temp have been explained. For the Tach and speedo, use the diag mode from above to put the needles back in the correct spot. The digital read out will display what the computer is reading, just match it the best you can.
Do the tach when the car is cold and wait for the RPM's to drop to 1000 rpms. Then put the needle on.
For the speedo, run the car up to 60, or as close as you can get it, lock in the cruise control, then put the needle on. If you don't have cruise, a passenger is helpful. I did mine at this speed cause I spend most of the time between 60 and 70, so that is where I wanted it to be most accurate.
Remember, the computer is calibrated to stock diameter tires, so if you have a different size, it will be off.
Hope this is what you are looking for.
Mike