As scook said you should have been using X3e for the last couple of years anyhow. That was the stable version. 
 
I would start there as that will keep you working in the environment your used to until you get your project finished. 
That said you can install the latest version of Splat, use melodyne to fix the track and re open in X3 to finish it off. 
There's not a huge difference really and Splat has so many better features that one is really crippling themselves staying in the past. 
 
But honestly, myself I just make people re sing the part in key. If they can't then they should take up knitting as a hobby 
 

Well, I was wondering if Melodyne needed some kind of first run input to work properly with X3. As a workaround, you could open your vocal file file in Melodyne, make your adjustments, save, then import into X3.

Success! I downloaded Platinum, and the Melodyne editor opens in the MultiDock when I select Create Region FX. Now I just need to learn how to nudge a couple notes up a bit without it sounding artificial, but I'll watch the tutorials again and practice a bit with it tomorrow. Thanks to all for the help, it is greatly appreciated!