Your particular setup may already make use of the routing tables, and changing the required digits will likely mean some rather extensive programming.
First- I assume you're using 2 MICS. What are the extension ranges at each of your sites? As lugerlover pointed out, to eliminate the dialed 9, the ranges will have to begin with different digits, and the lead digit cannot be the same as any assigned pool codes, etc...
Well, it might be easier to call a local Norstar tech.