custom date type in xml schema

Dear all,
         I would like to ask how to customize date type such as MM-DD-CCYY, or YY/MM/DD instead of the default CCYY-MM-DD in schema. 
        I have tried the following but the validation result is that the date value is invalid.
        Please help.
xsd:
<simpleType name='mydatetype'>
        <restriction base='date'>
            <pattern value='MM-DD-CCYY'/ >
        </restriction>
</simpleType>

xml:
      <birthday>10-29-2002</birthday>
Regards,
Hanna