Can you load/use custom forms from a C# AddIn in Outlook 2003?

Question

As part of a VSTO C# AddIn, I need to be able to display the category information on an e-mail in the message window/email item inspector (If it makes any difference, I don't need to display it when there is no category information) so that an end reader can see the category information upfront. I was told trying to replace the default outlook forms was a bad idea, so I made a custom one within outlook and published it as a template.

I was wondering if it's possible to call/use this template when the email item has categroy information. I know it can be done in VBA, but I want to stay away from VBA. Does anyone know how to call custom forms withing a C# AddIn in Outlook 2003? Additionally, does anyone know how to distribute the form with the AddIn installation?

Thanks for the help