From a service note sent to me by Ari.  Thanks, Ari, for this great information.

Applicability: 1992 to 1994 5-speed 9000 with TCS

bulletNOTE: On 1992 cars, the ABS ECU must be replaced with one from a 1993 or later car.
bulletNOTE: The TCS can be disabled by pushing the switch at speeds below 37 mph.  TCS function is disabled only until the ignition is switched off.  Each time the car is restarted, the switch must be pushed again.

Switch/wiring harness part number: 85 49 214

Sealant for ABS connector shell: 88 28 089 (I'm thinking that silicone sealant would do for this)

Steps:

bulletRemove the blank button from the switch bank to the right of the steering wheel
bulletRemove the "kick panel" (panel above the pedals) on the driver's side
bulletRemove the rubber grommet above the pedal assembly and make a cut such that you can pass the wire through
bulletThread the wiring harness from the switch opening in the dash down to the grommet location
bulletThread the wire through the cut in the grommet
bulletConnect the brown/white lead to the brown/white lead on pin 7 of the seat heater switch
bulletA connector is provided, presumably a crimp-on splice
bulletConnect the black lead to the black lead on pin 9 of the seat heater switch
bulletConnect the harness to the TCS on/off switch and install the switch into the dash (from the front)
bulletLubricate the black lead with a soap solution, then thread it through the grommet
bulletFit the grommet to its hole and seal it
bulletDisconnect the connector from the ABS ECU
bulletI feel sure this is the standard Saab connector, released by prying back the retaining clip, then rotating the connector around the opposite end. 
bulletSlide the rubber protective cover off the connector, then pull the shell off the connector
bulletInsert the black lead through the rubber bushing
bulletSnip the cable tie, then drill out the hole for pin 25 using a 4.5mm bit
bulletI make that to be around an 11/64" bit
bulletPin 25 is in the center row, 6th position from the cable entry end
bulletInsert the black lead's pin into the hole from the rear.  Tug lightly to check the retention
bulletPress down the seal
bulletI don't know what this means, but presumably, it will be obvious
bulletSecure the cable harness in the connector with a cable tie
bulletRefit the connector cover
bulletFit the rubber protective cover in place
bulletCarefully apply sealant around the protective rubber cover to form a moisture barrier
bulletReconnect the connector to the ABS module and secure it with the locking clip
bulletReinstall the kick panel above the pedals