I too have always thought it would be cool to do something like this. Unfortunately alarm systems (and other conventional battery backup systems) generally use SLA or gel batteries, which is what the link you posted is designed for.

I think what might work better would be an li-ion battery management chip designed for portable USB devices. The lights and other devices could run continuously off the battery, and the dynamo would keep the battery topped off. There might be some prebuilt modules floating around for this kind of thing, but I doubt there's anything that would be completely suitable off-the-shelf without some extra circuitry (for one thing the power draw would be a lot higher than what the chip was designed for).