as far as i am aware, you cannot. Apexi make a PFC boost controller, but it is $400-$700 extra!
there should be an inline filter between the pressure source and the controller unit, otherwise any crap can daamge the pressor sensor inside the unit.
Also, might be worth checking for a vacuum leak, because as Krishy said, it should read -99 at idle.
all else fails, do a reset (RTFM), and go see a tuner.