How do I Access iTunes not on startup disk?

To clarify, I have my 1.55 TB iTunes program on a separate disk from my current startup disk, and I am able to play the music on that separate disk. I would like to be able to access the music from my current startup disk, but I haven't figured out how to do so or even if doing so is possible.

That's the solution I was unable to find. I can't thank you enough.

But thank you, thank you, thank you.

Happy holidays and Prospero Año Nuevo.