New Legacy owner. Pickup wiring questions...

Hey, guys! I'm a newbie to G&L, got my first USA Legacy about a month ago. 2014 Vintage White with cream pickguard. I love it, except I prefer humbuckers in the bridge, so I got a used Seymour Duncan Little Screamin' Demon for it real cheap. The red and white wires are taped off, the green and bare ground are soldered together, so I take it all I've got to do is solder the hot black wire to the switch and the green/bare to the volume pot and that's it for standard humbucking operation? Will there be any problem with the stock Legacy neck and middle pups or the PTB controls not working right? Will there still be hum-cancelling in the 2 and 4 positions or will I need the Demon split?
In my almost 30 years of playing on and off, I do my own setups, but I've never done any of my own wiring before, so I guess now's a good time to start.
Thanks.

-Joe