I've flown 737 100-800 and they all had a ROTARY KNOB for the rudder trim-- I think the reporter has confused things with the aileron trim (KNOB on the 100/200 and switches from the 300 onwards.)
Same setup for the Lear 60. In fact it's two knobs one atop the other on coaxial shafts which must be activated simultaneously to cause trim tab movement. Apparently either Learjet or the FAA felt the extra protection against inadvertent rudder trim operation was needed. They are spring loaded rotary switches that return to the center (neutral) position when released.