You have to understand that the dock is just an image only. There are 3 transparent beecons that sit on top of the image.
Goto page 1 of this thread there are instructions on how to create the dock bar beecon then goto page 29 of this thread, Zentenario has posted instructions on how to add the transparent beecons. You might want to create the other beecons like the clock, etc to understand exactly how to create the beecons.