Although the TIME/DATE options can be found in System Preferences, as expected, the FULL format in the dialogue box shows the day of the week (e.g. Wednesday) in its FULL format; however, when I click OK to add the FULL format to the menu bar, it appears there in the abbreviated form (e.g. Wed).
My goal was to have the FULL format appear in the Menu Bar EXACTLY as it appears in the dialogue box in System Preferences
I just re-located this link, which I had trashed for lack of interest (after all this time), but
10.4: Easily add the date to the menubar may help you out.
The procedure doesn't work in Snow Leopard, but I have a recollection of its having worked in Leopard (despite its Tiger pedigree).
