What are you trying to do?

Do you want 2.0 from stereo inputs while still redirecting bass to the sub when listening to multichannel sources? If that's your goal, you may want to look at Pure Audio or Direct modes (as described on page 33 of the Outlaw guide). These disable bass management, which would mean 2.0 inputs would stay 2.0 even if your mains were set to "small."

Do you want 2.1 from stereo inputs? If so, are the inputs analog or digital? Digital sources would be easy, as the bass management will take care of things for you as long as you aren't using Pure Audio or Direct modes.