I will suggest an alternative to the above. The POD Xt is an audio interface all by itself. You will need to disconnect the Tascam and make the XT the audio I/O device. Use headphones.

This circumvents the Tascam altogether. Once you have your guitar tracks recorded, then you can remove the XT as the audio I/O device and use the Tascam for all of your other stuff.

With your method right now, you are converting A/D inside the Pod, then converting D/A at the pod into the Tascam, then A/D again in the Tascam. There's no need to do this as the XT is an interface all by itself.

If you don't want to do this, then you should be looking for an input V/U type applet for the Tascam, or inside of the PG product you are using that is pointing the the analog inputs of the Tascam.