I know this has being answered correctly by Gaia Clary , but I needed to do a similar thing, and it took me a little while to find the exact code needed, so here it is. 
I wanted to be able to pick some (but not all of the mesh select menus).The code below shows how I achieved this.
    
        bl_info = {
        "name": "Yomi_Pie_Menus",
        "author": "Oluwayomi Longe",
        "version": (0, 0, 1),
        "blender": (2, 73),
        "description": "Custom Pie Menus",
        "category": "3D View",}

    import bpy
    from bpy.types import Menu

    # Pie Select Mode - Tab
    class PieTabMode(Menu):
        bl_idname = "pie.tabmode"
        bl_label = "Select Mode"
        
        def draw(self, context):
            layout = self.layout
            pie = layout.menu_pie()
            
            #4 - LEFT
            # use the commented line below if you want to toggle Edit and object mode
            #pie.operator("object.editmode_toggle", text="Edit/Object", icon='OBJECT_DATAMODE')          
            
            pie.operator("object.mode_set", text="Edit", icon='EDITMODE_HLT').mode='EDIT' 
            #6 - RIGHT
            pie.operator("object.mode_set", text="Object", icon='OBJECT_DATAMODE').mode='OBJECT'
            
            #3 - BOTTOM - RIGHT
            box = pie.split().column()
            row = box.row(align=True)
            box.operator("mesh.select_mode", text="Vertex", icon='VERTEXSEL').type = 'VERT'
            box.operator("mesh.select_mode", text="Edge", icon='EDGESEL').type = 'EDGE'
            box.operator("mesh.select_mode", text="Face", icon='FACESEL').type = 'FACE'
            #8 - TOP
            #pie.operator("sculpt.sculptmode_toggle", text="Sculpt", icon='SCULPTMODE_HLT')
            pie.operator("object.mode_set", text="Object", icon='SCULPTMODE_HLT').mode='SCULPT'
            
            
    def register():
        bpy.utils.register_class(PieTabMode)    
        # or any other classes you add
        
        wm = bpy.context.window_manager
        
        if wm.keyconfigs.addon:
            #Select Mode
            km = wm.keyconfigs.addon.keymaps.new(name='Object Non-modal')
            kmi = km.keymap_items.new('wm.call_menu_pie', 'TAB', 'PRESS')
            kmi.properties.name = "pie.tabmode"    


    def unregister(): 
        bpy.utils.unregister_class(PieTabMode)
         # or any other classes you add
        
        for km, kmi in addon_keymaps:
            km.keymap_items.remove(kmi)
        addon_keymaps.clear()


    if __name__ == "__main__":
        register()