Update the WDS boot image to include the new third-party network driver

To do this, follow these steps:

Note: The following procedure assumes that the Windows Automated Installation Kit (AIK) is installed on the WDS server.

1. On the WDS server, click Start, click Run, type wdsmgmt.msc, and then press OK.
2. Under your WDS server, double-click Boot images.
3. Right-click the boot image that you want, and then click Disable.
4. Right-click the same boot image, click Properties, and then click General.
5. Note the name and location of the boot image that is displayed in the File name box.
6. From the Windows PE Tools Command Prompt, type the following:
   C:\program files\windows aik\tools\petools\copype.cmd x86 e:\windowspe-x86
   Note: Keep this command prompt window open for the next step.
   Imagex /info Drive:\remoteinstall\boot\x86\images\boot.wim
   Notes:
   Drive:\remoteinstall represents the path at which the Remoteinstall folder is installed.
   Boot.wim is the name of the boot image.
7. Note the boot index number of the bootable image that is displayed. To identify the boot index number, locate the line that contains "boot index: X."
   
   Note: X is the boot index number. The number indicates that image number X is marked as bootable and that the image is to be updated. The second image is the default image that you would typically modify. However, always verify which image is marked as bootable.
8. At a command prompt, type the following:
   Imagex /mountrw Drive:\remoteinstall\boot\x86\images\boot.wim 2 mount peimg /inf=driver.inf mount\Windows
   imagex /unmount /commit mount
   Notes:
   Drive:\remoteinstall represents the path at which the Remoteinstall folder is installed.
   Driver.inf is the name of the third-party driver.
   The Imagex /mountrw command mounts the specified image, with read/write permissions, to the specified directory.
9. Enable the boot image on the WDS server. To do this, follow these steps:

• On the WDS server, click Start, click Run, type wdsmgmt.msc, and then click OK
• Under WDS server, double-click Boot images.
• Right-click the boot image that you want, and then click Enable.
  
  Link: http://support.microsoft.com/kb/923834