How can I put a field's value in a Validator message?

[Yee, Richard K,,DMDCWEST]

I would like to include a field's value in my Validator custom error
message. In my validation.xml file, I have a msg tag defined with a
key="someProperty.errorMessage".  In my application.properties file, I have
defined my someProperty.errorMessage property as follows:

someProperty.errorMessage=You typed '{0}', are you stupid or what?

How can I access the field's value so I can set it in the arg0 tag for the
field?

Thanks,

Richard