VirtualDriveSet Portable 2.2

This is the code I use for the Tick5 game and it's fully commented in my source. This code backs up a copy of the .ini on the local machine if you have Tick5 permanently installed (per John's guidance). You don't need to worry about that since your program will be run from a portable device only so you can trim this code down when you customize the file names and locations.

Section "Main"
	ReadINIStr $DISABLESPLASHSCREEN "$EXEDIR\${NAME}.ini" "${NAME}" "DisableSplashScreen"

	FindProcDLL::FindProc "tick5gui.exe" ;if running, exit
	StrCmp $R0 "1" TheEnd
	
	StrCmp $DISABLESPLASHSCREEN "true" SkipSplash
			;=== Show the splash screen before processing the files
			InitPluginsDir
			File /oname=$PLUGINSDIR\splash.jpg "${NAME}.jpg"
			newadvsplash::show /NOUNLOAD 1000 200 0 -1 /L $PLUGINSDIR\splash.jpg

    SkipSplash:
        IfFileExists `$PROFILE\Tick5.ini` "" MoveIni                            ; Check if local Tick5.ini exists --  No: Goto MoveIni
            Rename `$PROFILE\Tick5.ini` `$EXEDIR\Data\settings\Tick5.ini.bak`   ; Backup the local machine's Tick5.ini file 

    MoveIni:
        IfFileExists `$EXEDIR\Data\settings\Tick5.ini` "" Execute               ; If settings saved from last time -- No: Run program to generate a new ini
            Rename `$EXEDIR\Data\settings\Tick5.ini` `$PROFILE\Tick5.ini`       ; Copy ini back to profile dir

    Execute:
        ExecWait `"$EXEDIR\App\Tick5\tick5gui.exe"`
        Rename `$PROFILE\Tick5.ini` `$EXEDIR\Data\settings\Tick5.ini`           ; Save settings back to portable
        IfFileExists `$EXEDIR\Data\settings\Tick5.ini.bak` "" TheEnd            ; Check if local Tick5.ini file backed up? 
            Rename `$EXEDIR\Data\settings\Tick5.ini.bak` `$PROFILE\Tick5.ini`   ; Return original ini file to the local machine

	TheEnd:
		newadvsplash::wait
SectionEnd

here was a really quick way i came up with it
here you go

$var = IniRead("Data\VirtualDriveSet.ini", "VirtualDriveSet", "Driveletter", "B:")
if FileExists ($var&"\") Then
	Run ("subst.exe /d "& $var)
Else
$var = "subst.exe "&$var&" \"
Run($var)
EndIf

this one will also look for the ini in the data folder
luv this program btw

Edit:
also do you really need all that code for the launcher?
here is a base you can use

;Copyright (C) 2004-2006 John T. Haller

;Website: http://PortableApps.com/PNotePortable

;This software is OSI Certified Open Source Software.
;OSI Certified is a certification mark of the Open Source Initiative.

;This program is free software; you can redistribute it and/or
;modify it under the terms of the GNU General Public License
;as published by the Free Software Foundation; either version 2
;of the License, or (at your option) any later version.

;This program is distributed in the hope that it will be useful,
;but WITHOUT ANY WARRANTY; without even the implied warranty of
;MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;GNU General Public License for more details.

;You should have received a copy of the GNU General Public License
;along with this program; if not, write to the Free Software
;Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.

!define NAME "PNotesPortable"
!define FRIENDLYNAME "PNotes Portable"
!define APP "PNotes"
!define VER "1.1.0.0"
!define WEBSITE "PortableApps.com/PNotesPortable"

;=== Program Details
Name "${NAME}"
OutFile "${NAME}.exe"
Caption "${FRIENDLYNAME} | PortableApps.com"
VIProductVersion "${VER}"
VIAddVersionKey ProductName "${FRIENDLYNAME}"
VIAddVersionKey Comments "Allows ${APP} to be run from a removable drive.  For additional details, visit ${WEBSITE}"
VIAddVersionKey CompanyName "PortableApps.com (John T. Haller)"
VIAddVersionKey LegalCopyright "John T. Haller"
VIAddVersionKey FileDescription "${FRIENDLYNAME}"
VIAddVersionKey FileVersion "${VER}"
VIAddVersionKey ProductVersion "${VER}"
VIAddVersionKey InternalName "${FRIENDLYNAME}"
VIAddVersionKey LegalTrademarks "PortableApps.com is a Trademark of Rare Ideas, LLC."
VIAddVersionKey OriginalFilename "${NAME}.exe"
;VIAddVersionKey PrivateBuild ""
;VIAddVersionKey SpecialBuild ""


;=== Runtime Switches
CRCCheck On
WindowIcon Off
SilentInstall Silent
AutoCloseWindow True
RequestExecutionLevel user

;=== Program Icon
Icon "${NAME}.ico"

Var DISABLESPLASHSCREEN

Section "Main"
	
	ReadINIStr $DISABLESPLASHSCREEN "$EXEDIR\${NAME}.ini" "${NAME}" "DisableSplashScreen"

	FindProcDLL::FindProc "PNotes.exe" ;if running, exit
	StrCmp $R0 "1" TheEnd
	
	StrCmp $DISABLESPLASHSCREEN "true" SkipSplash
			;=== Show the splash screen before processing the files
			InitPluginsDir
			File /oname=$PLUGINSDIR\splash.jpg "${NAME}.jpg"
			newadvsplash::show /NOUNLOAD 1000 200 0 -1 /L $PLUGINSDIR\splash.jpg
			
	SkipSplash:	
		Exec `App\VirtualDriveSet\VirtualDriveSet.exe

	TheEnd:
		newadvsplash::wait
SectionEnd

you can change the names in the beginning.

If Not FileExists("Data\VirtualDriveSet.ini") Then
	IniWrite ("Data\VirtualDriveSet.ini", "VirtualDriveSet", "Driveletter", "X:")
EndIf

OR

;=== Program Icon
Icon "${NAME}.ico"

Var DISABLESPLASHSCREEN

Section "Main"
	
	ReadINIStr $DISABLESPLASHSCREEN "$EXEDIR\${NAME}.ini" "${NAME}" "DisableSplashScreen"

	FindProcDLL::FindProc "PNotes.exe" ;if running, exit
	StrCmp $R0 "1" TheEnd

IfFileExists Data\VirtualDriveSet.ini Continue createIni
CreateIni:
		CopyFiles App\DefaultData\VirtualDriveSet.ini Data\VirtualDriveSet.ini
Continue:

	StrCmp $DISABLESPLASHSCREEN "true" SkipSplash
			;=== Show the splash screen before processing the files
			InitPluginsDir
			File /oname=$PLUGINSDIR\splash.jpg "${NAME}.jpg"
			newadvsplash::show /NOUNLOAD 1000 200 0 -1 /L $PLUGINSDIR\splash.jpg
			
	SkipSplash:	
		Exec `App\VirtualDriveSet\VirtualDriveSet.exe`

	TheEnd:
		newadvsplash::wait
SectionEnd