There is this installer.ms script in AUVN_247.mzp file:
try destroyDialog auvn_installer Catch()
rollout auvn_installer "Adv. UV Normalizer 2.4.7 Setup" width:210 height:60
(
	local oldmax = (MaxVersion())[1]<12000
	local usermacros = (symbolicPaths.getPathValue "$userMacros")+"\\"
	local userscripts = (symbolicPaths.getPathValue "$userScripts")+"\\"
	local userstartupscripts = (symbolicPaths.getPathValue "$userstartupscripts")+"\\"
	local tempdir = getFilenamePath (getSourceFileName())
	local title1 = "Advanced UV Normalizer"
	label lbl1 "Select an option:" pos:[5,5] width:200 height:13
	button install1 "Install" pos:[5,25] width:120 height:30 toolTip:("Install to \""+userscripts+title1+"\"") across:2
	button uninstall "Uninstall" pos:[130,25] width:75 height:30

	fn delDir DirPath = (
		if doesFileExist dirPath do (
			command = "RD /S /Q \""+dirPath+"\""
			HiddenDOSCommand command startpath:".\\"
		)
	)
	fn delFile filePath = (
		if doesFileExist filePath do (
			deleteFile filePath
		)
	)
	fn copyDir sourceDir destDir = (
		command = "XCOPY \""+sourceDir+"*\" \""+destDir+"\" /Q /I /S /Y"	
		HiddenDOSCommand command startpath:".\\"
	)
	fn uninst = (
		if ::OpenAdvancedUVNormalizer !=undefined  do (
			d=windows.getChildHWND 0 (title1+" v2.4.7")
			if d !=undefined do windows.sendMessage d[1] 274 61536 0
		)
		::OpenAdvancedUVNormalizer=undefined
		gc()
		sleep 1
		delDir (userscripts+title1)
		delFile (userstartupscripts+"auvn_autoload.mse")
		for i in (getFiles (usermacros+"AUVN*")) do delFile i
	)
	fn checkuninst = (
		if doesFileExist(userscripts+title1) or doesFileExist(userstartupscripts+"auvn_autoload.mse") then (
			if qb = queryBox ("You have the "+title1+" installed.  Do you want to uninstall it first?") title: "Warning" do uninst()
			qb
		) else true	
	)	
	on auvn_installer open do (
		if oldmax do (
			lbl1.text="Only 3dsmax 2010+ is supported!"
			install1.enabled = false
			uninstall.enabled = false 
		)
	)
	on install1 pressed do (
		if checkuninst() do ( 
			setWaitCursor()
			copyDir (tempdir+"scripts\\") userscripts
			sleep 1
			lbl1.text="Installed successfully."				
			try filein (userscripts+title1+"\\auvn.mse") Catch(Messagebox "There was an error installing Adv. UV Normalizer" title:"Error")
			if queryBox "Installation complete!\n\nGo to Customize -> Customize User Interface, choose \"AUVN\" in the Category list and assign the script wherever you want.\n\nOpen the Customize User Interface dialog now?" title: title1 do actionMan.executeAction 0 "59226"
		)
	)
	on uninstall pressed do (
		if queryBox "Are you sure?" title: "Uninstall!" do (
			lbl1.text="Started..."
			setWaitCursor()
			uninst()
			lbl1.text="Uninstalled successfully."
		)
	)
	on auvn_installer close do (
		if tempdir == symbolicPaths.getPathValue "$temp"+"\\auvn2\\" do delDir tempdir
		auvn_installer = undefined
		gc()
	)
)
createDialog auvn_installer style:#(#style_toolwindow, #style_border, #style_sysmenu)

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I too have instal.ms file in my ALL3DVRaySceneValidator category:"ALL3D" buttonText:"ALL3D Scene Validator v0.6" toolTip:"V-Ray Scene Validation Tool v0.6 for ALL3D" icon:#("ALL3DVRaySceneValidator", 1) mzp file:
(
 	filein "$usermacros\\ALL3DVRaySceneValidator.mcr"
	colorMan.reinitIcons()
	messagebox("Install notes:\n\n1. Go to Customize > Customize User Interface and select \"Toolbars\" Tab.\n\n2. Select \"ALL3D\" Category.\n\n3. Drag the \"ALL3DVRaySceneValidator\" to where you want it on toolbar.") title:"ALL3D V-Ray Scene Validator v0.6" icon:#information
)

I want you to create my install.ms file like AUVN_247's installer.ms.
Also, I want it to open Customize User Interface's Toolbar tab, after successful installation of the script.