Just got rid of the dock's background to use an image with geektool. I also changed the clock on the lower right corner. I liked the results so i thought i could share it with you . If you need anything, just ask
Ok, you can download these packs: [link] [link] or [link] Now, some of them include the path for replacing the icons. Others, even have a smart shortcut of the folder, so you basically only have to drag and drop.
Also, you can try this path OS: /system/library/coreservices/menu extras
If you need to change an specific application's menubar icon you have to right click the app (for example Dropbox) select "show content" (another finder window will open, unless you have TotalFinder in which case a new tab will open). Open the "Content" folder and check the "Resources" folder inside of it. It usually contains the menubar icons there.
I hope this is helpful buddy! Have fun customizing!