A coworker gave me their old G Tablet months ago, and the only thing I kept finding was that it was very hard to find all of the tools needed to modify the thing. So many download links are down, etc. I just wanted to post these on here.
I will take them down if I'm stepping on anyone's toes. I will not help you troubleshoot. I am not responsible for any harm caused by the things provided here, and I cannot claim that they came from reputable sources because I can't even remember from where or when I downloaded them.
I've included the drivers because they were harder to find. They're in usbpcdriver. I can't be bothered to reinstall them to find out which you need because frankly I don't care and you only have two or three options. Good luck.
By default nvflash_gtablet.bat flashes the files in its own directory. Just copy the files into where it's located.
The bootloader is contained on part9.img. If you want to flash CWM you will need to replace part9.img with clockworkmod.img for your particular bootloader. Just rename clockworkmod.img part9.img.
Hope this helps if anyone goes around looking to modify their device. Once again, please do contact me if you would prefer your work to be hard to find.