The yellow color that you hate is the aging varnish that protects the paneling. A light sanding and a new coat of varnish will bring back the brightness and hide some of the yellow, but a white-wash could be a problem. There are varnishes and lacquers that contain stain, but they are meant to be applied directly to raw wood.

Painting, staining and varnishing are not exact sciences. So, when a method of painting or staining is not normally recommended by the manufacturer (as in your case), then a test becomes the next order of business. And, although you might get lucky, using a varnish with white pigment over a yellowed varnish is risky.

There is a paint stripping product on the market called Peel Away. You paint it on, let it dry and peel it off. This method is easier than sanding and cleaner than other paint strippers. Once you've stripped the surface applying the white wash will be a breeze. And good luck!