the super easiest way to do this is to drag your applications folder (not the one in your sidebar in finder) to the dock(right next to the trash) and it is instantly there with the correct icon, or.........
okay, this requires just a few easy steps:
1) create an alias of your application folder in finder
2) drag and drop your alias to your desktop
3) select your application folder again and then press 'commad+i' or right/control click and click 'get info'
4)do step 3 for your alias
okay, now you should have two information windows open.
5)in your 'applications info' window there should be an icon in the very upper right hand corner, click it, and it will have a little glow around it (meaning it is selected)
6)copy it (command+c)
7) in your 'applications alias info' window, click the icon in the upper right hand corner so it is selected (and has that glow i mentioned before) and then past your applications icon (command+v)
done and done...it is easy, and maybe a lot more than a few steps, but that should do it for you.
-chris