Again, it's generally a very bad idea. I'd go so far as to say that the only
people that should even consider it would be those who know both the APIs
for initializing and hooking interrupts, as well as how to P/Invoke them
from managed code.  In short, the fact you're asking how it's done tells me
you don't know enough about the OS to prevent yourself from getting into
serious trouble trying to do it.

Why do you want to do it in C# and not in C anyway?