You won't be able to do anything on Twitter. The two ways to contact people on Twitter are to either tweet at them, using the syntax @username, or by sending them a private message. You'll likely get flagged and have your account shut down for spam if you write a bot to tweet all of them, and you can only private message people who are already following you.
As for Facebook, I don't believe you can share anything to people who aren't already your friends. Typically the way product/company and fan pages grow on Facebook are viral, with people sending the pages they like to all of their friends, or from links/like buttons on the company's website.
Though we don't know why you don't want to send them emails, I'd just like to comment on something subjectively. Personally, I'd be much more content with a company sending out a single email saying, "Hey, we've opened these social media pages and would really appreciate your support by following/liking them", rather than your divised alternative. It'd be way more of an invasion of privacy to have the company use my email to track me down and message me on multiple social media services than to send me a single email.