I mounted mine on the fork crown using the supplied bracket and used a couple of zip-ties to keep the gear/brake cables out of the way.
Luckily the bike had been fitted with a "Flinger" (see the EBC website) style nut on the back of the forks which meant that there was plenty of thread of the brake bolt engaged.
Never tried it upside down but given the way it puts more light in the right place by using a shaped beam, I'd be surprised if it was quite sub-optimal when mounted the wrong way up.