Mike, personally I play using the "pursed lip" method, but from what I understand the idea is to switch your tongue from one side of your mouth to the other.
For instance, if you normally play with your tongue to the left side of your mouth (playing out of the right side of your mouth) and you come upon a note to be played in holes 1 or 2, move your tongue over to the right side of your mouth (thus, playing out of the left side of your mouth) to play the notes. When you move back up the harp, you can move your tongue back over to the left side.
By the way, good for you for learn such a skill!