If you will be using page protectors, you don't need to worry about setting the chalk. I like to turn your page upside down on some scrap paper and rub the back to press the powder into the paper before putting it in the protectors, just to make sure that no powder will start sticking to the protector and look smudged.
For cards that will be handled, I spray lightly with hairspray, which WILL yellow over time so it shouldn't be used for long-term projects, or Blair makes an acid-free spray that does the same thing.
Hope that helps a little,