Corel PhotoPaint is a paint program, so I'm very sure you can use them there. I'm just not a whiz in PhotoPaint. (not a whiz in PhotoShop either, but can get around a bit)
I don't know whether the "layers" would all open though, since they are native to PhotoShop as .psd files. But surely the "flattened" .tif or .bmp would open and be useable.