For the DAW operator it is simply another over dub in a multi track process.
As you have suggested, import the music into SONAR. Set up another track and get it record ready. Get you monitoring set up to your satisfaction.
Press record.
Then mix to taste... it's the perfect way to learn how to think about EQ, compression and level balance.
Listen carefully and conjure up your instincts using every thing you've ever listened to to inform your decisions and then make small adjustements until you are happy.
If you share some reverb and maybe some mild compression on a bus for all the content it can have the effect of "gluing" the performances together so that they seem to have been done by a unified band.
Have fun.
best regards,
mike