Use pairs of fingers in the fretting hand start with fingers 1 and 2 for alternating notes. Then repeat for the next pair of fingers 2 and 3, then 3 and 4 (traditionally the weakest.)
This exercise can be repeated on lower frets to extend the stretch between the fingers by increments. I like to repeat it on 4&5, then 3&4, 2&3, then 1&2 for a thorough workout.
jdguitarsite 