Done this twice now. It really isn't that difficult. You'll need a 10mm and a 13mm socket (for linkages and arms), and a small Torx bit for the scuttle (T15 or T20, cannot remember), and about an hour.
Tip... (assuming UK car) Remove both side trims as well as the washer panel (2 torx per side). Washer panel (7 torx), this is teathered by the washer pipe, so it lays face down on the inlet manifold once out. Mechanism is held in with 2 bolts and 2 nuts (all M6, 10mm socket).
... Once the linkage is out (I think it was lift at the front to clear motor mounts first). REMEMBER how it came out, as I found it tricky to get it back again.
... I could disconnect the power wire as soon as the mechanism was out. Henry couldn't on his car. I guess I have a different casing. The plastic guard on mine has a small flap by the connectors allowing the cables to be removed and the work to continue on the bench. Made life so much easier.
... Motor has 3 M6 bolts holding it on, you can get a socket onto 2 of them, the other one needs a spanner. Motor drive is on splines, I had to "tap" the shaft with a hammer to release it. Watch for the plastic bush that is below the splines and falls off when you remove the shroud. Motor unclips easily, clean it.
Hopefully you haven't run out of daylight by now. Sitting in the dark with bits of wiper mechanism strewn everywhere.
... When refitting, the motor park position for mine had the linkage from the motor to the bar to the wiper mech in a straight line. Easier if you see it.
shows this linkage and bar, on mine it was dead straight when parked.
...When reassembled, run the wipers a few times without the arms attached to ensure that the motor is back at the parked position. Watch the splines to make sure they are going the right way.
... Make sure the arms are firmly reattached, and seated correctly. If not, they may slip and hit the scuttle panel/bonnet. (ask me how I know!)
Hardest part is getting the mechanism back into the car.