Hey @terry,
Thanks for reaching out!
This is unfortunately not possible with anything “out-of-the-box.” The easiest way to pull something like this off would be to put these widget-only events in some sort of category that exists only for internal use, like literally “widget-only” or “Admin: Widget Only” or something like that.
Any event that should only show in the widget: put it in this category.
Then, use custom CSS to hide the events in this category in the main calendar, but then selectively show these events based on the category if they happen to be in the widget.
To write custom CSS on your site, definitely check out a [free!] tool like Firebug if you use FireFox, or the Developer Tools for either Safari or Chrome. They have “Inspector” tools that let you zoom right over the element whose CSS you need to modfiy.
I hope these ideas help!
George