Customize Team explorer 2012 Code Review Request page

Hello,

I am working on customizing Team Explorer in Visual Studio 2012. I have added new field to "Code Review Request Work item". I would like to display that field in Visual Studio Team explorer "new Code Request" page and user should be able to save along with other fields such as Reviewers, Subject, comments . I am able to add field in section and save, but how can i get the required validation for that field.

Please help me on this !!

Thanks,
Sree

Sree