Transfer Cubase tracks into a Roland Boss BR 1600 - How to?

[CubaseToBoss]

I have a WinXP system and use Cubase SX3 to record rhythm tracks using
plug-ins (VSTi's).

A friend in another state has a Roland Boss BR 1600. I'd like to
record rhythm tracks on my computer using Cubase SX3, then take those
tracks and somehow use them with the Boss BR 1600 to record multiple
vocal tracks on the BR 1600, then mix them using either the BR 1600 or
Cubase's internal mixer.

Is there a way to transfer the rhythm tracks, which would take up
about 12 to 20 actual tracks per song, from my computer into a BR
1600? Am guessing it would involve burning the tracks onto a CD-r,
then transferring those tracks into the BR 1600 by means of its own CD
reader/writer, but am not at all sure of the procedure on either the
Cubase end or on the BR 1600 end.

Getting the tracks from my computer into his BR 1600 would be Step
One. Step Two would be transferring the finished vocal tracks from the
BR 1600 into Cubase SX3 on my computer.

Could someone please offer a step-by-step procedure for both Step One
and Two?

Thanks very much in advance for all suggestions.