Okay, first off to access to trainer lessons from the main menu, select "Training" then "Learn an Instrument", then select Pro Drums.
For this achievement you need to do the bottom 3 expert lessons titled Advanced Techniques, Advanced Beats, and Advanced Fills.
You have to complete every lesson in these three categories at 100% speed. I just finished this and it took some unique fudging of the controller to make it work, so here are my tips.
1st - You do NOT need 3 cymbals to do this, I use an ION kit and only have 2 cymbals. None of the lessons require the ride (blue) cymbal, so plug one cymbal into yellow and one into green, make sure the 4 pads are plugged in and you are set.
2nd - if you can't get a beat, try it at a slower rate and build up to 100%, also pay attention to the little tips that the game shows in the top right corner, they are very helpful.
3rd - I actually had to switch some of my inputs around. I am not sure if you can do this on the RB3 stock kit, but on the ION kit you can swap the inputs, meaning I can chart my high hat to my yellow pad instead of the cymbal to make some things easier.
On some of the disco beats, you can move the high hat yellow cymbal to the red pad, and the red pad to the yellow pad, and it is just like playing a disco beat in regular mode.
The last beat that I got actually took me quite a while and I ended up moving the inputs again. It was under advanced techniques and is called "triplets down the kit"
the chart is basically red, yellow, blue, bass pedal, but you need to hit the notes very quickly. I ended up making my kit where the red and yellow were swapped so instead of going LRRK (left right right kick) I went RLRK (right left right kick) and i got it on the first try after 30 mins of breaking a set of sticks and yelling at the tv trying to do it the 'legit' way.
Hope this helps, bottom line is that not everyone will be able to get this, I was a plat drummer from rb2 and it took me a lot of practice/time to get this. Good luck!