How To: Set My Custom Mail App As Default For Windows/IE?

I wrote a custom mail application in VB.NET and I want to set it as the default application to use for clicking mailto: links in IE and in general in windows. How can I do this? I've had success changing the default mail application in IE in the Tools->Internet Options->Programs menu, but that only allows Outlook, Outlook Express and Hotmail. I read that in order to use other apps like GMail etc you have to "install something."

Well, as a developer of a mail application, how can I get my own custom mail application into this list (as I assume I have to code/write whatever this "installer" is)?

Thanks in advance!