Wow, look what I just found!
http://www.ncaa.org/library/rules/2001/2001_football_rules.pdf
Here is some stuff I've been able to glean from this book WHICH CANNOT BE CUT AND PASTED BECAUSE OF ITS FORMAT SO I HAD TO WRITE ALL OF THIS STUFF!!!
Rule 2, Section 11, article 1 - reads:
Each goal line is part of a vertical plane separating an end zone from the field of play when a ball is touched or in a player's possession. The plane extends beyond the sidelines. (Exception: Rule 4-2-4-e)
Rule 4, Section 2, article 4-b reads:
A touchdown may be scored if the ball is inbounds and has broken the plane of the goal line before or simultaneous to the runner going out of bounds.
Rule 4, Section 2, article 1-a reads:
A player or an airborne player is out of bounds when any part of his person touches anything other than another player or game official, on or outside a boundary line.
Rule 4, Section 2, article 2 reads:
A ball in the possession of a runner is out of bounds when either the ball or any part of the runner touches the ground or anything else on or outside a boundary line other than another player or a game official.
So it appears from the above that
a ball in possession of a runner who is airborne is not out of bounds while the runner and the ball are still in the air - no matter if the ball and the person are in the air outside of the sideline. They, both the runner and the ball, have to touch something outside the boundary before being out of bounds.
And the goal line does extend past the sideline.
Which means that a runner still in the air but outside of the sidelines CAN score a touchdown if the ball breaks the plane of the goal line before the ball or the ball carrier touch anything outside of the sideline.
Or at least, that is how it reads to me.