How would I make this modded controller?

Using this http://llamma.com/xbox360/mods/extra-360-controller-buttons.htm, a Llamma.com guide for adding extra buttons, how would I go about making a circuit that presses one button then another rapidly? I cant use the old-school LED rapid fire technique, because my controllers aren't old enough.
So I need it to:
- Press one button then another
- Rapidly press
- run off controllers power

Thanks in advance,