Christopher Schlegel, one of our instructor here at Guitartricks as made a series a tutorials on how to mix minor pentatonic scales over major progression by spicing up the minor pentatonic "box" blues shape with notes from the major scales.

http://www.guitartricks.com/lesson.php?input=9940&s_id=217
http://www.guitartricks.com/lesson.php?input=10019&s_id=232
http://www.guitartricks.com/lesson.php?input=10023&s_id=244