When you're setting up your profile, there's actually a whole category set aside for script-writing, as well as communities and groups. Some people are playwrighters, some are screenwrighters, and there is a growing community for comic script writing.
Since this is my first official one and I've been procrastinating due to waiting to be "perfect", I'm using NaNo as an opportunity to hammer out a detailed outline, since that's how I like to work, and to start building my script. I have accepted that I'll likely be editing my script once I start thumbnailing, but that's fine with me, as long as I have SOMETHING to work from!
If you choose to do this, I wish you luck! I'm now 3000 words behind schedule lol, so if you join, I hope we BOTH get caught up.