An easy way to do a finishing pass in Cut2D, would be to define a copy of your cutting tool for "Roughing Pass" and define the bit radius larger than it actually is by the amount you want to remove in the finishing pass.
Then generate two toolpaths for your cut. The first one with the Roughing Pass defined bit, then a second toolpath using the defined bit which has the actual bit size.
If you have a 0.25" endmill, your "Roughing Pass" bit diameter definition would be 0.30" (a radius increase of .025) Which would cause the toolpath to cut the pocket an extra .025" away from the wall. Since the ACTUAL bit your using will cut .25", it will leave .025" of material on the wall of the pocket. The next pass, created with the actual tool diameter will remove only that .025" of material, giving you the finishing pass.