You can use water taken from a water change, that's probably the easiest and most eco-friendly. If you wanted you could use fresh SW
though, it really doesn't matter.
You really just need to cure it, not necessarily try to cycle it. Just let it sit in the water with a heater and a powerhead to keep the water moving and monitor the water parameters. no need to add any LR
, sand, shrimp or bacteria. All you're trying to do is ensure all the dead stuff on there isn't going to leech ammonia or other bad stuff into your tank. Then, once it's cured, you can put it in your tank and over time it will become live without affecting your tank in the process.