This may or may not work for you and do it at your own risk but I jut rooted and loaded a custom ROM to a LG Optimus S that many had said couldn't be done because of the OTA update that would put it out of the reach of the exploit. It required a little extra work, but was doable and only took me about 2 hours.
Now I am not 100% certain this will work for you because I don't have this particular device to try, BUT, the foundation of the rooting method is valid for it and should work for this as well, no harm in trying.
Get the drivers specific to your device from LG if you can find it and if not just get it here, this is not related to me but I got some stuff from them in the past and its been clean.
Then after that, try following the instructions put out here, note its for the Optimus S but the way to do it is the same for pretty much all the Optimus line, its your driver that is important and you can get that. You can use the Manual method if you know what you are doing and are comfortable with it, that's how I did it but you can also download the
optiauto.zip or .exe to do it as well so its somewhat automated for you.
Good luck with it, let us know how it goes and if you run into anything that you can't figure out, shoot me a message here and I will see what I can do for you.