Grant Permissions to List Items using existing SharePoint Group using Client Object Model

I have found examples on how to add users to SharePoint Groups using Client Object Model. Can anyone help provide an example on how to grant permissions to items in a List using an existing SharePoint group? I dont need to create the group in code, nor add users to the group. I also do not need to add roles to the SharePoint Group. I simply need to grant permissions to the List Item using the existing SharePoint Group.

Thanks for any tips provided.