I've installed one before....the Oakley directions work fine or if you need another set of instructions, email Oakley or download it off their site
you have to man handle the goggles to pull off the old straps to get those little tabs to go into the holes
the plastic around the goggles near the new holes is very pliable so don't worry too much about breaking anything
bend and twist is a bit to get the new nubs to fit into the holes
or do what I did....take your regular A frames, go to any seamstress and have them take the buckle off the back and add a Velcro extension to the strap
it works 1000x better than the helmet extender and will allow you to adjust the goggles any way you like