How you get less then 1 ohms for your grounding system?

The same way you decrease the resistance of anything else ... by providing more parallel current paths. That means running more conductors, and increasing the surface area of contact between your ground system and the earth.

But let me ask you a couple of questions in return:

1). Since the lightning current already flowed through a couple thousand feet of air before it reached your house, do you really think it will notice whether you have 1 ohm or 2 ohms or 5 ohms in the rest of its path to ground ?

2). Aircraft have really good systems in place to protect their avionics and communications from lightning. What do you suppose is the resistance of their systems to ground when they're in flight ?

Just asking.

Maybe there are other things about the grounding system that are more important, and have a greater bearing on the quality of your protection, than a few DC ohms in the path.