Art is spot on. Very light gear and holding the rod(s) are key. UL rods, 2lb test, and 1/16 oz jigs. Length of the rods, IMO, not very important.
We always use a minnow trailer. A lively minnow makes a huge difference, again, my opinion.
The bite that we were seeing at Alamo closely resembled an active minnow on really light gear, more or less a slight tick. The difference was it was followed by a very light drag where the rod had a slight bend. My guess is the fish was swimming with the very slow trolling speed we were using.
At this point the hook could be set. My experience with crappie is that they do a pretty good job of hooking themselves in normal situations. In the lite situation I would slowly move my rod tip forward (the direction of trolling) then let it go slack and let the line tighten back up watching and feeling for the fish to provide a little drag. Hook set at this point.
Good luck if ya venture out.