I'm a little inexperienced at this method, but I belive you could.....
Out of your board from mic input (we'll call it 1), auxillary bus your vocals to an echo or reverb processor, return your effected vocals to a different channel (we'll say 2), but don't have it assigned to any tracks. Only monitor Channel 2, which will have the effect, and record from channel 1 which will be a clean vocal.
I believe it is as simple as that, but if anyone can correct me, I'd appreciate as well, the whole concept is pretty new to me.
Justin