126: What if I don't have an Escape key?

  Type `C-[' instead.  This should send ASCII code 27 just like an Escape
  key would.  `C-3' may also work on some terminal (but not under X).  For
  many terminals (notably DEC terminals) `F11' generates ESC.  If not, the
  following form can be used to bind it:

  (define-key function-key-map [f11] [?\e])  ; F11 is the documented ESC
                                             ; replacement on DEC terminals.