Try downloading the Windows 8 32bit drivers if using 32bit WinPE boot media. If this is an Intel network adapter, HP's website for that 600 G2 does not appear to have a 32bit driver download for Windows 8.x only for 64bit unfortunately.  However, Intel does provide this I-219 32bit driver(s) so try those.  https://downloadcenter.intel.com/download/21642/Intel-Network-Adapter-Driver-for-Windows-8-?product=82185

The reason for this is because OSM 9.1 is based on WinPE 5.x which is Windows 8.0/8.1.  Injecting those drivers should allow the network to work.  First extract the drivers from the Intel package though since the package will try installing when double clicking, which something like 7zip can be used to do this or other similar program.

After extraction, each driver must be tried to find out which one works with that hardware, there are quite a few in the package and any one of them could be it, but the most likely drivers to try first is one of four for 32bit:
ProWin32\PRO1000\Win32\NDIS63\e1c6332.inf (Windows 8)
ProWin32\PRO1000\Win32\NDIS63\e1d6332.inf (Windows 8)
ProWin32\PRO1000\Win32\NDIS64\e1d6432.inf (Windows 8.1)
ProWin32\PRO1000\Win32\NDIS64\e1r6432.inf (Windows 8.1)

To test it quickly, place the drivers on a flash drive.  Boot into OSM 9.1 and press ALT+TAB to get to the command window.  Try pinging the OS server or any internet address.  If it doesn't work, then load the driver manually and see if the 8.0/8.1 driver will resolve it before injecting it into the WinPE image.

The command to do this is:

drvload "path to .inf file".  For example: Having the above (NDIS63 and NDIS64 folders) on the root of the flash drive E would be:

drvload e:\ProWin32\PRO1000\Win32\NDIS63\e1c6332.inf
drvload e:\ProWin32\PRO1000\Win32\NDIS64\e1d6432.inf

After each driver load, wait about 20 seconds or so and try pinging the server or internet website.  If it does not work, then try loading the next driver and so on.  Once it starts working, that will be the one that needs to be injected into the WinPE boot image in order for the 600 G2 model and other models using that same Intel I-219 hardware.

In Radia 8.1 for Intel NIC use flat driver from  http://ftp.hp.com/pub/softpaq/sp72501-73000/sp72516.exe 

Hi Adam,

While that SP72516.exe may work for Radia 8.1 if the WAIK tools were used, I can't find drivers in that package that are for Windows 8/8.1.  I don't believe that will work for Radia 9.1 OSM because the WinPE version is based on Windows 8/8.1 (Using ADK 8.x for WinPE creation).  The Intel I-219 is what Nathan is looking for though to make this work, but I'm pretty sure the Windows 7 drivers will not work in this case.  Thanks.