Is there an easy way to have MarketPress use an external database for all functions?

I will have about 100 WordPress installations all using the same product list in MarketPress. I’d like to have a single database from which to manage products, leaving all cart, gateway, shipping, etc. functionality to the local WP database. Is there any way to accomplish this without rewriting all of the MarketPress functionality – and therefore losing the ability to update the plugin?