Not sure if there will be any problems to try this in Win8, but hopefully this information from my G75VW Win7 unit can help.
My notebook with original ASUS image still has this icon and can be re-pinned to the taskbar (if the software has been installed already and the shortcut unpinned) by showing hidden folders, looking under C:\Program Data\ASUS Resource Center to right-click and pin the ASUS Resource Center shortcut to your taskbar to get it back as below.
If you still have the original ASUS image with 'eSupport' folder under the C: drive, looks like the Win7 installation program can be found under C:\eSupport\eDriver\Software\ASUS\DeviceStage_(G series).
It may not be available for download on the ASUS site, so we may need to get you a copy if you don't have it anymore.
Otherwise, you could probably create your own taskbar shortcuts using that icon if you prefer (as long as you have the icon)?