Found a solution to avoid having to install MOOSE.

Now MOOSE can be copied into the mission file, but you'll need to
include a "do file" action of moose.lua in the mission file and copy the
rest of the MOOSE files to the MIZ file.

Moose/Menu.lua

@@ -0,0 +1,107 @@
+--- Encapsulation of DCS World Menu system in a set of MENU classes.
+-- @classmod MENU
+
+Include.File( "Routines" )
+Include.File( "Base" )
+
+
+MENU = {
+  ClassName = "MENU",
+  MenuPath = nil,
+  MenuText = "",
+  MenuParentPath = nil
+}
+
+---
+function MENU:New( MenuText, MenuParentPath )
+
+	-- Arrange meta tables
+	local Child = BASE:Inherit( self, BASE:New() )
+
+	Child.MenuPath = nil 
+	Child.MenuText = MenuText
+	Child.MenuParentPath = MenuParentPath
+	return Child
+end
+
+COMMANDMENU = {
+  ClassName = "COMMANDMENU",
+  CommandMenuFunction = nil,
+  CommandMenuArgument = nil
+}
+
+function COMMANDMENU:New( MenuText, ParentMenu, CommandMenuFunction, CommandMenuArgument )
+
+	-- Arrange meta tables
+	
+	local MenuParentPath = nil
+	if ParentMenu ~= nil then
+		MenuParentPath = ParentMenu.MenuPath
+	end
+
+	local Child = BASE:Inherit( self, MENU:New( MenuText, MenuParentPath ) )
+
+	Child.MenuPath = missionCommands.addCommand( MenuText, MenuParentPath, CommandMenuFunction, CommandMenuArgument )
+	Child.CommandMenuFunction = CommandMenuFunction
+	Child.CommandMenuArgument = CommandMenuArgument
+	return Child
+end
+
+---
+
+SUBMENU = {
+  ClassName = "SUBMENU"
+}
+
+function SUBMENU:New( MenuText, ParentMenu )
+
+	-- Arrange meta tables
+	local MenuParentPath = nil
+	if ParentMenu ~= nil then
+		MenuParentPath = ParentMenu.MenuPath
+	end
+
+	local Child = BASE:Inherit( self, MENU:New( MenuText, MenuParentPath ) )
+
+	Child.MenuPath = missionCommands.addSubMenu( MenuText, MenuParentPath )
+	return Child
+end
+
+MENU_SUB_GROUP = {
+  ClassName = "MENU_SUB_GROUP"
+}
+
+function MENU_SUB_GROUP:New( GroupID, MenuText, ParentMenu )
+
+	-- Arrange meta tables
+	local MenuParentPath = nil
+	if ParentMenu ~= nil then
+		MenuParentPath = ParentMenu.MenuPath
+	end
+
+	local self = BASE:Inherit( self, MENU:New( MenuText, MenuParentPath ) )
+
+	self.MenuPath = missionCommands.addSubMenuForGroup( GroupID, MenuText, MenuParentPath )
+	return self
+end
+
+MENU_COMMAND_GROUP = {
+  ClassName = "MENU_COMMAND_GROUP"
+}
+
+function MENU_COMMAND_GROUP:New( GroupID, MenuText, ParentMenu, CommandMenuFunction, CommandMenuArgument )
+
+	-- Arrange meta tables
+	
+	local MenuParentPath = nil
+	if ParentMenu ~= nil then
+		MenuParentPath = ParentMenu.MenuPath
+	end
+
+	local self = BASE:Inherit( self, MENU:New( MenuText, MenuParentPath ) )
+
+	self.MenuPath = missionCommands.addCommandForGroup( GroupID, MenuText, MenuParentPath, CommandMenuFunction, CommandMenuArgument )
+	self.CommandMenuFunction = CommandMenuFunction
+	self.CommandMenuArgument = CommandMenuArgument
+	return self
+end