As a gift to my boyfriend this year, I was hoping to buy or somehow put together an external (USB or Bluetooth) keyboard to be used alongside his Macbook's built-in keyboard. He is a grad student studying linguistics and commonly needs a wide variety of phonetic symbols. Since there doesn't seem to be anything on the market to fit this need, I thought I could buy some sort of programmable keyboard/keypad, but I couldn't find any that labelled mac-compatible.

I'm not a Mac user myself, so I don't know a whole lot about them. I've found pre-made keyboard layouts that should work perfectly for what I want and software to help me design my own (Ukelele, which can be run inside a virtual machine). The one thing I can't find an answer to that I would really like to know is if he could connect a keyboard (wired or wireless) to his Macbook and use two different keyboard layouts simultaneously.