Here is an app note from Maxim describing how to implement a digital potentiometer to adjust the output of a boost converter. Digipot is controlled through two push buttons. One controls the direction of the wiper, while the other moves the digipot wiper in the selected direction. [via]
The digipot is implemented on the DC/DC boost converter’s feedback loop, adjusting one of the resistors in the loop.
Connecting the wiper of IC1 via a 10k resistor to the FB node of IC2 sets that feedback according to the voltage on IC1′s wiper. The equation for setting the output voltage precisely is a complex one that includes the resistances of the feedback resistors and of the digipot, but it can be simplified by calculating voltages at the extremes of the wiper setting.
App note: Pushbuttons Control Regulated Switching Converter - [Link]