Is it possible to construct an adjustable output switching power supply based on the MC34063? I read over the On Semi datasheet and app notes but didn't see any examples of an adjustable output application, although I did have find another article about High-Power Adjustable Switching Power Supply based on the MC33060 http://www.apogeeweb.net/article/62.html.

Is it just a matter of replacing the "R1" and "R2" resistors with a potentiometer and then calculating the other components values based on a Vout in the middle of the the target Vout range (i.e. so for a Vout of 5-12V, you'd base calculations on 8.5V)?
Thanks!