The Waldorf Iridium is, amongst many other things, a sampler. And so many instruments have already been sampled – you will just have to load the samples to the Iridium, and place them in a patch.
This post will try to create a patch with the sounds of a Yamaha CP70 electro-acoustic piano, and have a small script do most of the work. If you are kind of lost here, read the „Not-so-grand-piano“ post first.