The aim here is to incorporate StackOverflow popular answers into Visual Studio\'s Exception Assistant.
I wanted to extend it as well. Doing a bit of research it seems its not possible.
Unfortunately this is not possible. We will consider this when we do our future planning for the Visual Studio debugger though.
Thanks,
Brad Sullivan - Program Manager - Visual Studio Debugger (source http://social.msdn.microsoft.com/Forums/en-US/vsx/thread/3b045e98-081c-4540-b27b-3121245e53ee/)