As a short term solution I\'m trying to jam a windows form \'usercontrol\' into a WPF application. I see in the WPF application view that I can add a \'custom windows form
You can't really add it as a control to the toolbox like you could for a Windows Forms Application. What you should do instead is "host" the user control inside of the WPF application.
See how to do it on MSDN.
Here's an example of how to use a masked text box (which you can easily modify to use your custom control):