Here's a better way:

keybindings.el

(defun jeg2s-yank-and-select ()
  "This is a test command for how to create a selection."
  (interactive)
  (let (deactivate-mark)
   (kill-new "selected")
   (yank)
   (exchange-point-and-mark)))
(global-set-key (kbd "C-c y") 'jeg2s-yank-and-select)

; See http://www.gnu.org/software/emacs/manual/html_node/elisp/The-Mark.html#index-deactivate_002dmark-2507