I made an attempt to transfer the most useful drawing from my notebook. I don't have a good program at home for drawing schematics, so please excuse the crudeness of it.
Not shown are the bits where the N-channel MOSFETs are used to switch the main LEDs. That part is pretty straight forward, though. I hope this helps. If you build it, post up here; I'd love to see what somebody else does with it.