change date format from "mm-dd--yy" to "yy-mm-dd" in manager side

hi all

i want to change date format for all pages in admin side .

i mean not only for site=>New document=>Page setting

can we do it from manager/media/script/datefunction.js and manager/media/calendar/calendar.html

can we do changes in "datefunction.js" or "calendar.html" so that it will be reflected in all pages.

so every time when calendar is called it will display date in yy-mm-dd format .

so that it will get reflect in all pages in admin side.

thanks in advance
joseph