Well, you -would- have to be able to physically report to a headquarters. For the US, that'd be in California (and in some cases, Texas). For EU, that's apparently Ireland and France. I've looked at getting a job in Blizzard before (They were looking for forum moderators a while back), but even the most simple jobs require you to be able to make a physical appearance at one of their headquarters.
If a position isn't listed on their careers page, they likely aren't looking for someone in that field. Best you can do is keep looking and checking for an opening.