The known issues document in the download center contains the correct locations.
it should go in:
C:\Documents and Settings\<Your User Name>\Application Data\Adobe\Dreamweaver CS4\en_US\Behaviors\Actions\WA Validation Toolkit\Apply Client Validations\WAFV_Required_C.js
and:
C:\Documents and Settings\<Your User Name>\Application Data\Adobe\Dreamweaver CS4\en_US\Configuration\Commands\WAFV_Required_C.js