LShift UP::Send, (
RShift UP::Send, )
LShift & F13::
RShift & F13::
Karabiner is pretty good though, and you can select certain keybindings to only work in emacs.
I've also remapped CONTROL to CAPS LOCK, a more common re-binding to save one's left-hand from endless torture and mutilation!
On GitHub https://github.com/tekezo/Karabiner
It's also pretty simple to extend Karabiner with XML scripts.