I only mix and master my own tunes and the tunes of some clos friends.

It might be good idea to ask for a reference mix/master they really like. Talk about the loudness wars and what they expect about that.

Encourage them to be honest about your mixes and masterings, you can and will learn from them.

Random thought: There could be a function that allows you to put your skype name on your profile so others can add you and talk about techniques. Would help people who want to get in touch with each other speed up the process.

I think there isn't a specific technique that will get you there. It is a combination of great chords, clever layering, great mixing and in the end a pretty loud master.

For example in his track '43' on that huge second drop there isn't really a lot going on: you have the kick, drums, bass, his amazing chords, white noise and some background atmospheric elements. However, each sound plays its role perfectly. In this genre, reverb plays a pretty big role, I think that ArtsAcoustic reverb or Valhalla will work pretty good.

It's all about filing the frequency spectrum correctly and giving each element it's own space and role. When you combine all that, you get a huge wall of sound.