This was done as I bought a Reloop Terminal Mix 2 DJ Controller for portability - I hooked the master output up to my mixer and voila! 3 decks.
All done live with no sync buttons and manual mixing (that's why it sounds a bit dodgy in places) on that controller, a Denon DNX1100 mixer, a pair of Technics SL1210 M3Ds with Dicers & Serato Scratch and Serato DJ.