The problem in this case is that HP never released a firmware update for this drive, and there are no other OEM firmwares available for GT30L drives either. In order to create a RPC patch there needs to be a firmware available first ...
This LG drive is based on a Panasonic chipset so dumping the firmware from it in a format which one could use to flash back is not quite available yet. At this stage it is possible to dump the firmware in a RAW format, but that can't be flashed back to the drive as it is ... you can find more details in this thread: viewtopic.php?f=2&t=47776
If you're happy to give it a try, you might want to use DevilsClaw's Flasher to try creating a RAW firmware dump for your drive and post it in the thread I mentioned above ... you can do that by running flasher from a command line with these parameters:
flasher -d 1 -l firmware.bin 1 80000000 00200000
That way at least we would have a raw firmware dump available for GT30L drives, which is far better than no firmware whatsoever.
For the time being though, the easiest solution would be to use AnyDVD to deal with the region restrictions.
If you don't want to use AnyDVD then there might be a riskier last resort alternative: to crossflash the drive to a GT30N model, but if you do that you will lose LightScribe support and won't be able to go back to the original GT30L firmware (since there is no firmware available for it). I would not recommend this for the time being... especially without having even a raw firmware dump available for your drive, so better stick with AnyDVD.