Hey CJay and Daveny5,
CJay especially, since you also have the Presonus FS Project, maybe I can share with you what I tried, but haven't had too much success yet:
1) From the back of the FS Project, connect a cable from the sends 1 and 2 to either the mic in or line in on the Digitech Vocalist
2) From either the L and R Line Outs from the Digitech Vocalist, connect a cable to any input on the front of the FS Project
3) In Sonar, set up a new Stereo Bus. Point your main vocal track to the bus using a send. Set the outputs of the buss to whatever inputs you used on the FS Project.
4) Create a new track, set the inputs to the vocalist's outs.
When I tried doing it this way, I was getting bleed for some reason from a few of the other audio tracks (such as a drum and guitar sound), and I'm not sure why. But it semi-worked! How are you connecting it?