This is practically impossible. The only pizza shop that has the resources to even CONSIDER doing this is Dominos or Papa John's. Not that they would (they're not that crazy), I'm just trying to illustrate the amount of cash needed to do this. It would require accessing the code from Radiant, which would cost you more money than the pizza shop makes in twenty years.
You need to look at a different POS. One that is natively suited for this task, or wait for Radiant to integrate this feature. I think there are POS systems that could handle this, but they are not suited for restaurants, more like retail. If I remember correctly, I have found e-commerce products that can (barely) handle a POS STYLE front end as well.
Save yourself the time, tell the client that it is not possible with Aloha.