Modifying automatic brake application increments

[KickingRocks]

I'm working with a particular interior where when the 'A' key is pressed, the ER and brake pipe draw down to around 40 lbs. How do I modify it so that each time the 'A' key is pressed, the ER reduces by 2 lbs (as is the case with most other locomotives in Trainz that make use of the Westinghouse)?

Thank you!