I don't seem to be able to in my 2001 SR5. When I pull out of my country lane onto the busy highway the right rear tire slips on the loose gravel shutting down power, for what seems like and eternity, and I fear for my life as the oncoming traffic approaches fast. Then I get my traction back and lauch at full power to avoid being rear ended!
Use you're own discretion...but you can pull the connector off the lower portion of the master cylinder. The TRAC VSC lights will be on, but your ABS still works. No more annoying grinding of the VSC alarming every time you corner, or hit a dirt road.
According to my owner's manual, and also other sources, 4-Lo + locked cancels VSC and changes A-Trac to a more aggressive braking without cutting engine power. In addition 4-Lo unlocked does not allow VSC to function below 18 miles per hour. Also 4-Hi locked cancels VSC as well.