The long and short of it? No, it's not really doable in a Windows OS. I suppose the one trick you could try is setting up a program like Windows AnonIRC on a friend's computer somewhere. AnonIRC basically acts like a regular IRC server and lets you log into it, then bounces you over to whatever IRC server it's connected to in turn.
It's not a perfect solution, but if your domain has been unfairly banned from a network and you don't mind being a bit sneaky, that's a way out.