The short answer is that tangs normally will fight with their image if you tape a mirror to one side of the tank. Some use a picture instead, but I like the mirror as the image moves. This may occupy the tang enough to let the cbb settle in, but that will depend on the individual fish. I would only give this a try if you quarantine the cbb first and get it eating without harassment from the tang.
What I would do is:
1. Get a good cbb - either one that is eating at your lfs one from a quality supplier like LA or DD. Put the cbb in quarantine for 4-6 weeks and make sure it is eating well. This will involve offering live blackworms in addition to both Hikari and PE mysis, spirulina enriched brine, and chopped scallop, clam and shrimp from your grocery store.
2. Only after the cbb is eating very well, put it in an acclimation box in the dt for at least a week so the tang sees the cbb but can't get at it. Some keep the newly-introduced fish in the acclimation box longer.
3. After that week is up, and about 1 hour before your lights go out, tape a mirror to one end of the tank. Wait until the yellow tang finds the reflection and starts fighting it, and then release the cbb 15-30 minutes later. You want the tang occupied and the cbb to have enough time to explore the tank before lights out.
Make sure there are plenty of hiding places for the cbb.
When you feed the tank, put in the food that the tang eats first (e.g., I use spirulina flakes) and then after the established fish start eating, immediately put in the live blackworms you will be feeding the cbb until it gets established in the tank. It will help if you feed the cbb at a different place in the tank from where you feed the other fish, but that will depend on where the cbb comes to the surface. If you feed your dt on the right side, perhaps you could condition the cbb to eat on the left side of the tank while in quarantine.
