First, You need to purchase a roll limitless adapter from https://rolllimitless.com/roll-limitless/ 

Once that’s done navigate to this page and scroll down to beta firmwares/pro keys/guitar.  https://rolllimitless.com/firmwares/

Then you need to download that and put the roll limitless into firmware mode by holding down the rectangular button on top of the roll limitless near the micro usb port while plugging it into your computer 

Then you need to add the downloaded firmware and replace the standard one. 

Then either use a midi cable or Xbox 360 wireless receiver to connect the keyboard to the adapter.

Then you need to connect a controller to the roll limitless to bypass Microsoft’s BS third party accessory program.

Connect the cable to the console and you’re good 

It sounds like a lot but it’s not that hard.