Pretty simple to do. Unscrew the "phillips" head nut. It is actually more like a cylinder with a big cross cut in the end. A flat screwdriver is usually a better choice than a Phillips. Clean the threads on the truss rod shaft and the internal threads on the nut. If you want to use a little lube on the threads something on the dry or gel side of things is best. Some guys use paste wax, some use anti-seize. Forget WD 40 (WD 40 is not a lubricant!) or any of the other liquid oils. They will make a mess and can cause the wood to swell. When that happens it makes it hard to turn the nut. Put the nut back on and make the adjustments.
Again, you might want to examine the depth of the tech's experience. It takes a good bit of torque to twist off a piece of 3/16" mild steel even with a T handled wrench. Generally speaking, the nut will emit a loud squeek long before the metal begins to tear. Those who ignore the complaints of metal will live to regret it. That is, if they are lucky and the metal is small.
With your experience and tool box it might be advisable to purchase a copy of the
Guitar Player Repair Guide. It is an easy read. It will save you money. Well, except for the brand new specialty tools you will buy.