Just found the Volvo Technical Bulletin instructing garages how to emission test cars with HP ZF-22 autoboxes for anyone who's got one:


Volvo TSB 2525, 9/91:

Before beginning the "High Idle Emission Test Sequence" make sure the car is at operating temperature. Place transmission into "park" and switch the ignition off for 30 seconds. Restart, but DO NOT move the selector through the forward or reverse gears before or during the test and DO NOT EXCEED 2000 RPM. The first stage of the test is at 1850 rpm for 30 seconds, the second stage is at normal idle for 30 seconds. If you fail the test and have to do it again, then DO NOT proceed with the programmed catalyst preconditioning test sequence. Abort the test, place the transmission into "park", precondition the catalyst at 1850 rpm for 4 minutes, then allow the engine to revert to normal idle and check the tailpipe emissions. Under no circumstances must you exceed 2000 rpm during any part of the test.