No blow-by-blow account for this subject, just a photograph of the end result.
Airbrushed Railmatch Frame Dirt for the underparts, with Weathered Black addded for the sides and ends. Weathered Black for the tops of smokebox, boiler and cab, with Mig Productions Black Smoke pigment on the smokebox and cab roof. Small quantities of Mig Productions Industrial City Dirt, Dark Mud and Track Brown in appropriate places around and about and some AMMO by Mig Fresh Engine Oil on the coupling/connecting rods. Wet paint was manipulated with a white sprit dampened wide flat shader brush and a couple of areas were tackled with a soft cotton bud to impart a vague sheen. A hint of Weathered Black was added to wheel centres and axle box covers.
I noticed that the Railmatch jar I opened for this model has a new lid arrangement, and it seems (so far) to be much better than the previous fragile plastic lid with paper insert.