How to enable Play Store auto-update for just a few apps? As the title says, I'd like to enable auto-update for trusted apps (e.g. Google apps), but if I open the app in Play Store and check Auto-update, I get the question "Auto-update is currently disabled for all apps. Do you want to enable it? You can always change this in Settings. Data charges may apply." Now, if I select Yes, auto-update is turned on for all apps and I have to deselect each one separately.

What I'm looking for is a way to enable auto-update, deselect all apps from auto-update and manually select which apps are allowed to auto-update (i.e. opt-in instead of opt-out).

Running stock 4.2.2 on Sony Xperia Z. I haven't rooted the device so solutions without root are preferred.

EDIT: The situation turned even worse. Now, if I have several apps waiting to be upgraded and I select Update all, I get a popup for each and every app asking "Auto-update has been disabled for [app], are you sure you want to update?". Seems like we're being driven to enable auto-update for all apps, and I don't like it.
You can do that with Titanium Backup Pro's Market Auto Updates… feature.