Код:

Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Msi.Package\shell\uniextract_sub]
@="Извлечь"
"Icon"="C:\\Windows\\system32\\msiexec.exe,0"
[HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Msi.Package\shell\uniextract_sub\command]
@=hex(2):22,00,25,00,53,00,79,00,73,00,74,00,65,00,6d,00,52,00,6f,00,6f,00,74,\
00,25,00,5c,00,53,00,79,00,73,00,74,00,65,00,6d,00,33,00,32,00,5c,00,6d,00,\
73,00,69,00,65,00,78,00,65,00,63,00,2e,00,65,00,78,00,65,00,22,00,20,00,2f,\
00,61,00,20,00,22,00,25,00,31,00,22,00,20,00,2f,00,71,00,62,00,20,00,54,00,\
41,00,52,00,47,00,45,00,54,00,44,00,49,00,52,00,3d,00,25,00,55,00,73,00,65,\
00,72,00,50,00,72,00,6f,00,66,00,69,00,6c,00,65,00,25,00,5c,00,44,00,65,00,\
73,00,6b,00,74,00,6f,00,70,00,5c,00,55,00,6e,00,70,00,61,00,63,00,6b,00,00,\
00
"HKEY_LOCAL_MACHINE\SOFTWARE\Classes\Msi.Package\shell\uniextract_sub\command": cтрока в реестре:
Распаковка происходит в "%UserProfile%\Desktop\Unpack" - для Windows 7.
Для XP сменить на "%UserProfile%\Рабочий стол\Unpack".