Hey this post is a day old an noone's flamed him yet?
In general, I think running high and low beams are not reccommneded, because you run a good risk of overheating (fire) the ground wires and melting the lamp housing. And then there's the whole legal discussion in which no-one cares if you say it's only for offroad, etc etc ad nauseum.
It's technically possible, but you will be better in the long run with dedicated offroad lights.