Is this the thread you found?: http://cs.trains.com/mrr/f/88/p/178279/1956313.aspx#1956313
Note that there is a link in the thread to a BLI webpage called fine tuning your Q2. You might find this helpful even if the thread does not answer the switch question.
By the way, did the loco come with an exploded view diagram where you might find the switch? I searched the BLI site and did not find a diagram.