This has to be done manually. Keep changing price for product B until its share matches A. Remember that you can interpolate between price levels you measured in your study so you can work this out to a high degree of precision in terms of price. Also, remember that you can assign the price values to the levels so instead of specifying "1" to mean price 1, you could specify "125" dollars if you associated 125 dollars with level 1. By assigning level values, you can then directly specify exactly the monetary value in the simulator rather than having to convert to level 1, level 1.1, etc.
To assign prices to level values within SMRT, click:
Market Simulator + Assign Level Values...
