If you look at the back of the CDJ1000s you’ll notice there is one connector glaringly absent, the USB-port. This means there is no way to let the 1000s “talk” to your computer, let alone use them as controllers for Serato.
Obviously you could go the DVS route, using TimeCode CDs. Unfortunately I think the NS6 is not (Serato) DVS-ready and probably never will be.
So, apart from hooking up your CDJ1000s as audio devices and using the NS6 as a glorified analogue mixer (no FX to be used as those come from Serato), there isn’t much added value.
As you might have noticed around here, we are not big fans of buying obsolete technology if you want to go into digital DJ-ing. So, we would never advice you to get CDJs if you already have a perfect controller like the NS6. If you are, however, set on buying CDJs for whatever reason, you’d be better off getting a pair of 850s which CAN be connected through USB and ARE supported natively by Serato when used in conjunction with a Serato-supported device (the NS6).