Hi,
Not exactly what u need, but the below expression will validate YYMMDD format
^((\d{2}((0[13578]|1[02])(0[1-9]|[12]\d|3[01])|(0[13456789]|1[012])(0[1-9]|[12]\d|30)|02(0[1-9]|1\d|2[0-8])))|([02468][048]|[13579][26])0229)$
I am not a regEx geek, so cannot modify it for youer needs, but hope it helps.
Please refer to
http://regexlib.com/Search.aspx?k=date
Anubhav Kumar