Here some illustrations to set up the "broadcasting" function of Synergy. You have to use the broadcasting version from this post:
http://www.dual-boxing.com/forums2/viewtopic.php?t=15

1. Open Synergy and locate the "Hot Keys" button.


2. In the new window click on the left "+" button.


3. In the new window, place your cursor in the blank text box and press a button you want to use as your “Broadcasting” toggle key, the click “OK.”


4. Now, Click on the right “+” button. (notice your toggle key in the left window)


5. In the new window make sure the “Toggle keyboard broadcasting” is selected. You don’t have to check any other boxes if you don’t want to. Click “OK.”


6. Your broadcasting key is now almost set up. Click “OK.”


7. Click “Test” to test your toggle key and other features OR just click “start” and then “ok” when the confirmation window appears.

8. GO PWN SUMPUM! Enjoy.