(whee, I totally screwed up email structure!)
I think a first good step, if we do it, is to figure out who is going to do
it. Just ReMo members, or anyone in the community who wants to? I
personally think that latter would be good, "We are Mozilla, ask us
anything" sounds pretty cool :-)
Next, after we decide who, a when needs to be decided. They post "major"
IAmAs in the sidebar, and I think this would qualify as that
(webdev/security did!).
After that, we would probably message the moderators of the subreddit and
tell them all the details, give them some verification, whatever else they
need.
Then we do the IAmA.
In theory.