Adding JavaScript to WP Dashboard

Hi,

I want to add a JavaScript "Feedback" or "Support" widget (Zendesk or something similar) to the public area AND admin area of a WordPress multisite installation. Adding it to the public side is easy. But what's the best way to do it in the Dashboard? I know there are certain recommended ways to modify the admin area, especially to make it update-safe.

Any ideas would be appreciated.

Thanks,

Mark