I need a way to force the customer to specify an attribute that will apply to all products in an order. The attribute must be the same for every item in the order and I need to prevent checkout if this selection hqs not been made. I also need to have this attribute displayed in the packing slip. I have tried every way of hacking existing methods but keep up coming up blank. the customer must be able to change the attribute from order to order so it can not be fixed to the customer.

This is the only thing holding mydevelopment up so I am very anxious for a solution.