Since the derived policy class is marked as Serializable the value of the JsLintPath property will be persisted and available when the policy is evaluated during check-in.
The other interesting piece of the custom policy is of course found in the override of the Evaluate method as shown below.
- Download and extract the *.vsix file from the provided zip.
- Install the *.vsix by double clicking the file.
- NOTE: If Visual Studio is open when you perform the install you may need to restart Visual Studio before you can continue with the next step.
- From Team Explorer, right click the project where you want to enable the policy and select Team Project Settings->Source Control... from the context menu.