You could download the Massey tape saturator (along with the other free goodies on his site. Amazing free plugins!!!)
Duplicate the original vocal track and delay the start of the original a few ms (to give the effect of the time delay created by re-tracking).
Place the tape saturation plugin on the duplicate track
Hey presto!
Play with the tape saturation and start time of the original track to get the sound you want.
D
