[OS X Emacs] key remapping for a Command key?

[siemsen at ucar.edu]

In Aquamacs 2-preview6, what is the Lisp syntax to map Command-Shift-7 to a function?  My ~/Library/Preferences/Aquamacs Emacs/Preferences.el file contains lines like

   (global-set-key [f15] 'myfunction)

I want a similar line that maps Command-Shift-7 instead of F15.  What's the Lisp syntax?

-- Pete