i use a uphoria usb interface with mic and midi inputs. using the asio driver you can hear the backing through headphones and as there's no latency you can record the vocal automatically in sync with the backing track as you hear it.

i'm assuming you want to record a new vocal track over the exisitnig BIAB backing and that you have a usb interface as i'm sure they all work the same way.

an audio interface is virtually essential if you are doing a lot of recording and theya re not prohibitively expensive.