Remove the glovebox -- six screws around the perimeter and one 10 mm bolt
below by the door.
Pull the glovebox out, unplug the bulb connector.
Before removing the ECU, disconnect the battery or pull the "Trionic" fuse
Move the carpeting away.
Unlock ECU harness by pulling the lever and unplug it. Undo a screw
in the lower right corner. The ECU slides down.
The new ECU plugs right in. After the installation, perform an
adaptation run by doing a series
of full throttle accelerations in high gear from 2000 to 4500 RPM.
It helps if you can find a long road going uphill.