The problem with double-sided adhesive Velcro is that it needs the two sides to align for a lasting hold. That doesn't happen when you have a curved surface and a flat one. To fix this, turn to Sugru.
Over at the Sugru blog, readers are talking about their favourite ways to use Velcro and Sugru together for various purposes. A theme that pops up often in the blog is using Sugru on a curved surface to make it flat, and then put Velcro on it. This way, the Velcro gets a firm grip when stuck together, provided the other part is on a flat surface too.
A neat example of this is how one reader fastened vacuum attachments to his cleaner:
I added some Sugru 'ears' to wind the cable below which keeps it tidy and out of the way of the air vents. I then added a Velcro pad to the plug and the body to keep the plug in one place. The nozzles have the same Velcro pads. I guess these could have been done with double sided adhesive, but building the round nozzle up to a flat surface with Sugru makes it work better.
7 clever little ways to combine Velcro + Sugru [Sugru Blog]