Hi Shad,
Yes it is possible to integrate this into your own admin panel and indeed this is something that I often do as customization work.
However it isn't possible to give any generic tips as to how to do this as clearly this will depend on each administration panel and the specific requirements of each.
Basically you will need to remove the login system (there is a simple check for this in the index.php file) and replace it with your own. At the very simplest level you will need to identify between the two user levels, 1 and 2 where "1" is the main admin level and has access to the various calendar configuration tools.
Also bear in mind that the code is designed to show the calendars (on user level 2) according to their "id" so you may need to adjust this too depending on what you want to be able to do.
Clearly to do this you will need PHP knowledge however you may not need to adjust the JavaScript.
Hope this helps

Chris