This shot in this set shows the technique I used--employing two flashes, one underneath with a blue gel, and the second flash 90 degrees camera-left.
Additional tricks picked up along the way:
Use a skewer or similar to mark your focus point
Use a large dropper so you won't need to contantly 'reload.'
Hand-hold nothing. To increase the keepers, you have to eliminate every opportunity for error. Hence, the old lab stand. Camera was on a tripod, and I used an SC-17 to connect my sb-800, since there is too much delay using the wireless mode. The second flash (blue, underneath) is an old, non-dedicated unit, fired at 1/16th power.