I'm not usually much of a linkinista guy, but this was cool so I make exceptions. In opposition to much of the aimless chatter that happens on NewMusicBox (yeah yeah, here too), composer Erik Spengler has written a comprehensive and readable primer on turntablism for his ilk.
On one hand this seem a little late (not for Spengler, who's been doing this for years) but a cutting-edge DJs now uses the wheels of steel as mere controllers for digital media. Of course, to the perspective of turntables as instruments it merely enhances that idea. And it certainly answers the question of performance of electronic works.