can you get the end of the cable out of the caliper hook? if so, get some mole grips on the metal part AFTER the thread that the cable comes out of, and then go nuts with the plusgas and spanners. for mine I had to jam the molegrips against the strut and cracked the smaller locknut off, then try to free the larger nut off. if theres not a chance of doing that you'd have to try and hold the cable further up, but you run the risk of damaging the threads or the sheath that runs over it.
for adjusting it (on the side i could do at least!) what I did was wind them back up the thread so theres enough spare cable to get it back into the hook easily, then pull the cable end so the nuts are resting against the hub. tighten the larger one up and when you've got just a smidge of free-play in the cable, do the lock nut up
mine now comes on nice and tight after 2 clicks
