It need passionate driven commitment persistance to master any instrument. Touchstyle technique is the main focus to enable the student to play 2 guitar parts at the same time independently. It's a new challenge as this technique is considered unique.
Practical material I teach encompasses: strenghtening hammering / tapping technique for 8 fingers, legato technique, playing both hands independenly, chord voicing, percussive thumb, etc.
For the double neck that I use is 14 strings (7 strings each neck) as it gives more optional note positioning, hence it's easier to develop greater musical ideas. It also has greater range notation than normal 6 string guitar.
Nevertheless, this technique could be applied in normal electric guitar too (though there would be some restriction).
All videos taken at Tapping Guitar Showcase at Queenstown Public Library, September 2016