Frankly, rebuilding the the functionalities of the AdminTool from "outside" is not an easy task, considering that you will need to know a lot of intricate details of the server core.
I wouldn't recommend doing anything like that. We have already built a very convenient tool which can be published online anywhere and integrated with any other control panels.
What we'll do is providing a selection of vital Server params via JMX for external monitoring applications. This is scheduled for the final release, so it will still take a bit of time before it's out.