Hi!
I don't see an answer here, yet, so...
If it's just an online thing, you can post here on BFA.
If it's early work or rough ideas, you'll probably just want a thread on "hacks -> brainstorming & development".
If you need multiple grouped threads, you can ask lumpley (Vincent Baker), as per the "dedicated hack forums" thread on above sub-forum.
If you're publishing, I *think* the deal is if you're just using vague mechanical concepts or something, like most of the existent hacks do, no real permission is needed, but you should probably contact Vx and let him know anyhoo. For more specific stuff, like using the actual moves, text, IP of AW itself, I expect you'd have to work out something more specific.
But, yeah, for publishing definitely talk to him and see what's up, my answer could be wrong!
Now, the stuff about forums (above) may have changed with the spring cleaning, so I'm not 100%, but I'd start there (there being either a thread on b&d or a dedicated sub-forum).
- Alex