Hi Bilal,
I unfortunately don't know much about how to modify those pages, as this modification isn't directly supported. However, I wanted to add some clarification regarding the throttling settings available for System and Domain Admins. Please note that the domain's throttle limit takes precedent over the user's limit.
Let's say you set the domain throttle limit to 1000 messages per hours, and set each user to 500... Even if the Domain Admin changes the users limit to 2000, the domain limit of 1000 will still be enforced. As soon as 1000 messages per hour have been sent from the domain, it will be throttled.
Andrea Free
SmarterTools Inc.
877-357-6278
www.smartertools.com