I know this thread is very old but I thought I could chime in if this can help someone.
Take a look at this site.. http://thehelmethook.com/products/the-helmet-hook
If you have bar weights on your bike, you can use it and if not, you can always get some, they are cheap. You CAN also ask them and they will drill one
out for you to slide OVER the handlebars, like in this picture... helmet-hook-on-buell-next-to-switch-housing-20140516_125502_800-text.jpg
Note that it was never designed as a SECURE device, anything can be stolen BUT, you CAN lock it if you'd like and it seems to me that it's a better option. Later guys.