Ddcboyle They provide nuts to attach the spacer to the car, and you use your original to attach the wheel to the spacer like you would normally.
Don't get me wrong these appear to be decent spacers, just non standard stud length unfortunately.
Well just had a stroke of luck, as the nuts tightened onto the bolt instead of the alloy, when they sheared, the shaft that was left was loose to the touch so they just spun off!
Here's a pic of 1 of the sheared lock nuts, the last surviving lock nut and a new bolt which there was a set of in the boot. Notice the big difference in the size between the lock but and the normal nut.