I was trying to integrate the update in already downloaded installation so when I install it again, it would install with update. There seems no official way but here I founded something I am going to try out!
The Apple System Image Utility (SIU) for Mac OS 10.6.X lets you build a package based bootable OS DMG that has never been booted on a physical machine using the Mac OS X installation DVD. The benefit of this is that it's, for the most part, machine-independent as long as you use the latest version of the Mac OS X installation DVD. This ensures maximum compatibility with the largest number of Mac models. There are some exceptions to this, such as when a new Mac requires a specific driver that has not made it onto the latest version of the Mac OS X installation DVD.
The Apple SIU is included with the Server Admin Tools. You can download it by going to Apple - Support -Downloads and entering "server admin tools" in the Search Downloads search field. Follow the instructions below for building a package-based machine-indepedent bootable OS DMG that can be deployed with the Reinstall Computer command. These instructions are specific to version 10.6.X of the Apple SIU. Before starting, make sure that you have already configured a customized Absolute Manage agent PKG, either by editing the DefaultDefault.plist manually or with the Agent Customization Script from the Absolute Manage Resource Center.
1. Mount the ServerAdminTools10.X.X.dmg disk image and launch the ServerAdministrationSoftware.pkg to install it.
2. Launch SIU from /Applications/Server/System Image Utility.
3. Insert a Mac OS X installation DVD and then select 'Mac OS X Install DVD' under Sources in the left hand pane.
4. Pick 'NetRestore Image' for the image type and click the Customize button.
5. Agree to the SIU licensing agreement and the Automator Library window will open.
6. Enter the info for a default local admin account to be added into the 'Add User Account' workflow box. If youwould like to add any additional user accounts drag in the 'Add User Account' workflow item from the Automator Library window and place it just below the one for the default local admin account.
7. If you would like to leave out any unnecessary components that you do not want to install, such as foreign language translations or printer drivers, drag the 'Customize Package Selection' workflow item from the Automator Library window into the SIU window.
8. Uncheck both the Default and Visible columns for any items you'd like to exclude from installation.
9. Drag the 'Add Packages and Post-Install Scripts' workflow automator item from the Automator Library window into the SIU window.
10. Drag any PKGs you'll like to install, such as a combined OS update PKG installer, into the 'Name' area of this workflow item.
11. Add your customized Absolute Manage Agent PKG installer to the end of the list of PKGs to install.
12. In the Create Image workflow box, enter a name for the volume this disk image will be restored to into the 'Installed Volume' field.
13. Use the 'Save To' field to pick a location where your DMG will be output to.
14. Click the Run button and enter your password when prompted.
15. In the Finder browse to the .nbi folder at the 'Save To' path and mount the Netinstall.dmg found there.
16. In the NetInstall.dmg go to /System/Installation/Packages. Copy the System.dmg there to your hard drive and rename it something that makes more sense for you. This the bootable OS DMG that you will be using to reimage clients with using Absolute Manage Reinstall Computer command. You can also use Disk Utility to restore it locally also.
17. Click the Save button to save the workflow for creating this disk image again so you can easily modify it later and rebuild it by adjusting the list of PKGs to be installed.