I find it hard to believe that snuck isn't an accepted word, as I've *always* used that instead of "sneaked." Seriously, who uses "sneaked??"
Example: "The kid sneaked into the darkened theater and took a seat on the front row." "The kid snuck into the darkened theater and took a seat on the front row."
Seriously, which of the two would you prefer to see in a work of fiction? To me, it's snuck all the way - always has and always will be.
(This is one reason I'm dreading the day I have to buy a new computer, as my 10,000 or so spell-check corrections would no longer work...man, that's going to be a cruel bummer to be dealing with that.)