Export Maya model in OBJ format and then import it into UV Layout. C=Cut Seams. D=Drop Patches. Shift+Enter=Seperate Patches. Shift+F=Relax UV's. Export model with relaxed UV's as OBJ.
Import OBJ with relaxed UV's into ZBrush. First use brush in Draw mode, then Edit. Save as a tool in ZTL format. Use Move brush to make large scale changes. Use Sculpt brushes to add finer details to the model. Shift=Smooth. These changes will be used to generate a normal map.