'Modify only' will do exactly what you need. If you tick that it won't install the update(s), it'll just modify and leave them within the downloads folder ready for you to install at your leisure

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 Mac OS X 10.6.4 Retail || Intel Core2 Duo E8200 2.66GHz || Gigabyte G31M-ES2L || GeForce 6600 GT 128MB || Realtek ALC883 Audio || Realtek RTL8169 LAN || Samsung SpinPoint F1 1TB HD || Sony Dual Layer IDE DVD RW DW-D22A || Apple Aluminium Keyboard || Mighty Mouse

 MacBook Pro || 2.4Ghz Core 2 Duo || 200Gb HD || 2Gb Ram || NVIDIA GeForce 8600M GT

 iPhone 4 || 16Gb