In Store Pickup & Taxes

My client offers in store pickup, and we have that created as a free shipping option just fine. But we are running into an issue with taxes and the in store pickup option not being charged if the customer has a billing or shipping address that is not within the location created for taxes. Has anyone found a way to collect taxes via this method or some other way?

You would probably have to use both the 'calculate_cart_taxes_pre' and 'calculate_cart_taxes_post' hooks to change the shipping info in the cart for the user if the free shipping method is being used, compute the tax, then change it back again.