The UE customs require you to visit an audiologist who will take a particular type of mold of your ear canal. The description is on their site, once you click on 'further details'.
The monitors themselves are very interesting, they have several variants, I think the one's Freddy chose are top of the line (and not at all cheap), they have three independent drivers in each module (bass,mid,highs) as well as miniature crossovers. It's insane.
On a slightly different topic, you all talk about vintage speakers for your home setups, but the studios that mixed most of the music you listen to, did so most probably on Yamaha NS-10m studio monitors. Why not just get yourselves a pair of those or a pair of studio reference monitors if you're interested in flat response? I never got all this business about speakers. The problem is that all of them have their unique characters, but if you want a true representation of the music as it was performed, wouldn't it be best to try and replicate the exact conditions in the studio at the time? Just some thoughts