I want my users to input a date in the format dd/mm/yy

I know some of them will mis out the separators and enter for example
140301 for the 14th March 2001, but Excel changes the date to something
totally different.

How can I create a mask (like in Access) so the separators are already
displayed in the cell? For example the cell would look like / / and
when the date is input it automatically jumps over the separator.