Edit: Thought you were talking about a Tablet PC.
Try this page.
Specifically it's unlocked by earning the Mission Engineer Accolade which is awarded for getting a number of the AE Badges
Huh, never even knew about that. I have the badge on Mouse Police at least.
my lil RWZ Challenge vid
Dumb question. Is there a way to unlock the tabelt write emote? Mine is greyed out.