Heat it up to break the thread-lock compound. Tool selection isn't going to matter much if the thread-lock won't release. Probably the reason you stripped it in the first place? Anyway, after it's properly heated, you should be able to get it out with vise-grips, or by cutting a slot for a standard screwdriver. The issue you're facing is the lock-tite though - deal with that and then you have options.
I've also had some luck with stripped hex heads by simply hammering a flat-head screwdriver of the right size into the remaining corners, but keep in mind, everything like that you try will make the problem worse if it doesn't work.