I have a slightly similar problem.
My client is offering purchased in specified quantities, 10 packs, 50 packs, 100 packs etc so they have attributes for each product, around 5 per product.
The client needs to be able to select multiples from these attriburts to make up the number they want to order.
Eg. Select 200 packs + 50 packs to order 250 packs.
Because of this they are setup as checkboxes, since nothing else would allow this, however, if the client just hits add to cart then it add the product, no value to it nor any numebr of items are added.
This is of course not a good thing, however by the same token I do not want to set a default to it either, more because they have 100s of products and it would take an age to do.
Can anyone help me work out how to simply dissable the add to cart button from working properly until a selection has been made, but still have the button clickable with a popup window telling them they need to make a selection.
Many thanks



