I am myself a Linux user and don't know a thing about peripherals in OS X, so would anyone have any advice concerning this situation? Would any of these generic USB HID devices work fine or should we better try getting something else?
I used a Logidy UMI 3 back when I was a OS X user, then I went Linux, use the same pedal and works great. Has a jack for an expression pedal but I haven't tried using that yet. Works out of the box for me in Ubuntu, don't remember having problems using it under OS X. The little configuration utility where you change the types of messages it sends out only works in Windows and OS X I think, I haven't tried running it in WINE but it isn't a huge deal. I think as a default, it send MIDI notes 60 62 and 64.
It's basically a little metal wedge with 3 metal push buttons, aforementioned expression pedal jack in 1/8 inch form, USB-B port out the back, little LED that lights up when you push the buttons. It is a little noisy, but I haven't found it to be noticeable in my live percussion/electronic activities (although you prob don't want a mic TOO close to it). Durable as heck, no need for an external power source.
I think they're around 70 or 80 bucks?
Derek