I believe the very worst thing you can do is encourage people to spam Square-Enix. Especially through the support channels. Not only would it be extremely rude - it also gives them an idea that you don't really know what you're doing, and you're just competing to see who can shout the loudest.
Personally, I will not take part in that. Even though I do approve of the cause.
Instead, organize an actual petition. Ask for signatures here. Once you have a reasonable amount, send
one, well-worded e-mail with a link to the petition page. They might not add it anyway, but at least you did it in the most calm, professional manner available to you.
I'm not big into web petitions in general, so I don't know where to find all the right tools, but a quick search on Google yielded this page:
www.ipetitions.com. Seems decent. Free, as far as I could tell.
Make an actual petition, post a link, and I'll definitely sign.