Add Shopper Fields/VM Default Not Usable

[toad78]

I'd like to know how to add Shopper Fields to the either the 'Payment' section or the 'Bill To' section of the Cart page. The default options VM give are not flexible.

We want users to be able to select items from a drop down that need to be visible. VM's default would not make these items visible/usable unless the user accesses the 'Ship To' box or if they register (which our users are not required to do). Therefore, making these items more visible during the most common checkout processes would be best to have them easily visible.

Does anyone have any suggestions on how this can be done? Or maybe a plugin that would work for this?