You can save any custom text as your default Usage Rights request message. Here’s how:
Open the [...] menu on the asset you want to request Usage Rights for.
Select Request Usage Rights.
Edit the message in the text box where you see the default Usage Rights request.
When you’re ready, click Save as Default Message.
From then on, your custom message will appear in the text box every time you request Usage Rights. You’ll always have a chance to customize it further before you hit send.