Go as you would go about your average MTB Wallride but start slowly turning verticaly.Once vertical start tapping X(Accelerate)button like a mad hoe and while doing that gently lean forward because if you lean forward to sudden you will pop off, if too slow your front end will come up and you will pop off too.Im suggesting you try it in the canals in LS, more exactly the place where stuntman did the MTB Wallride.
This is highly experimental, if it doesnt work keep trying because it is hard.If someone who has no problems with it could make a video of it I would appriciate it.The Vertical Wallride still counts as the Wallride its just in a vertical direction.If you're thinking that Im making all the inventions up in the past few days you're wrong, I just play SA a lot and I try new things everyday.