How to add custom validator to rich:calendar?

[statelessbean]

Hi,
I use rich calendar on my page. User can set date of birth via calendar or input text field.
So there must be added validator with my custom messages, how can I do it, or how to change present validation messages?

Now when user input wrong date I get

registerForm:date: '2006/12/02' could not be understood as a date. Example: 2007-12-20

This is my calendar code

<rich:calendar id="birthDate" enableManualInput="true" ajaxSignle="true" datePattern="yyyy-M-dd" value="#{registerAction.birthDate}" />