How the !§$%&!!! do you carry a M18 or similar motocycle D-lock?

I actually saw a guy today who put his long d long through the rails on his saddle, then locked the thing below the rear triangle on the frame. You'd have to be sure your saddle was up high enough but it kept the thing in place quite nicely.

For the first time, this is an interesting suggestion. Ideas like that were exactly what I was looking for.

BTW Tiswas, sorry for missing your velcro idea. might work, but sounds wobbly to me.