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.