To be brutally honest reason is the worst sequencer to do this with, that's why I moved to ableton.
Most sequencers have dedicated Audio & MIDI tracks whereas reason does not deal with Audio, so your only choice is loading into one of the samplers (NN19 or NNXT) or getting yourself recycle, which is a fair few quid, and making rex files to chop up.
Also if you want to edit the acapella wave form at all, you'll have to this process all again in a seperate audio editor.
My suggestion is using the rewire feature to a program which can sequence audio, such as Cubase or Ableton live, or if cash is a factor, then get a cheaper multi-track recording program such as Adobe Audition.
Then run all your reason MIDI data & Synths through this, and you'll have complete control over your acapellas at the same time