So, my wife just surprised me with a Das Keyboard 4 Ultimate (with blank keys, which is awesome for Colemak). I had mentioned that I wanted a mechanical keyboard and so she found one on sale recently. I absolutely love it, I am becoming a typing nerd.

Anyway, the point of this discussion is that I have a num pad for the first time in a long time that I am starting to use. I find it really useful because I type a lot of patent numbers which are long numbers set off by commas. The problem is that the num pad only has the period and no comma in it. Since I also use the period and the dash in combination with numbers as well I would like to change the plus key to a comma. I have had no such luck, though. Karabiner has an option to change the num pad plus key, but the only choices are shift, command, control, and option. I might be able to customize the XML on Karabiner, but I have no idea how to do that. The keyboard layout in my macbook does not show a num pad, so I can't try to change it over there either.

Anyone know how to do this?