I can vouch for ControllerMate, and though the full product is not free, the evaluation version gives you enough output configuration options (up to 10) to map all your pedal buttons and then some, for free. You can also map separate keys to the press action and release action, so no need to open up the device, or buy two, or anything.
These pedals with three buttons have a pretty great build quality and heft.
Infinity USB Digital Foot Control with Computer plug (IN-USB2) http://amzn.com/B002MY6I7G
As for the software for button customization:
I can vouch for ControllerMate, and though the full product is not free, the evaluation version gives you enough output configuration options (up to 10) to map all your pedal buttons and then some, for free. You can also map separate keys to the press action and release action, so no need to open up the device, or buy two, or anything.