The manual for the G5/SP/LM says:
Bush, Steering Lock 17-18kgm (122-130 ft/lbs) - that's for the top lock nut.... I know, seems extremely tight, but it can handle it. I think I settled at around 100 ft/lbs on mine once I was all done with the adjustment.
As far as how tight to make the steering head nut (below the top triple) then as other have already mentioned, it's by feel. I think it was Rdkyll here (where is he, is he ok?) suggested the bike to be on a stand, tighten, then loosen until the steering flops with a tiny bit of resistance on its own from left to right, or something along those lines and I could be quoting that incorrectly too. In my experience, I got mine too loose at first (not intentional) and it's pretty obvious when hitting the front brake only as the head will feel as it pops out a bit, so I made that my indicator; I'd tighten a bit, go around the block on a straight stretch then hit the front brake multiple times almost as pulsating (on safe surface of course :-) ) and see how it would feel, repeat until it felt right. I ended up being happy with the results. I think a lot of people develop a technique, so this is just how I do it now.