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.)
The 737-700 that I flew had a rotary knob for the cockpit door control and it was very close to the rotary control for rudder trim.
SW