Ah ok, I saw this which is what I was using. I guess both ways work :P
GraphicUtilities.drawModel(this.bot, g, npc.getGridX(), npc.getGridY(), npc.getZ(), npc.getModel());
this draws the actual model, you can draw the outline of the entity as well:
and using your way will result in the entire area being filled. The main difference is drawModel will draw the in game model, where your way will fill in the entire area occupied by the entity.