PLINE is not going to be even close to the same function. For plines, you will have to get the list of coordinates, reverse the list, draw in a new pline and delete the old pline. It will also have to be different for ACADLWPolylines and ACADPolylines. And that's assuming that every polyline ever selected will be made of straight segments. If it has any curves, the fun will REALLY start.