Al, I don't have my rulesbook with me, but I believe the rule regarding linemen in motion says UNLESS he first established himself as a back (by stepping off the line and resetting), he must be at least five yards behind the LOS at the snap if he's in motion. I'm reading this as saying he can go in motion directly from his spot on the line, but he better be moving backwards rather quickly to get at least 5 yards back before the snap.
And obviously if he's in motion five yards behind the LOS, there's no way he can be considered one of the 7 men on the line at the snap.
In short, a wide-out on the line cannot be side-stepping along the line until the snap.