I believe an officer salutes any rank who holds the VC first and he acknowledges it.
In fact there is nothing in writing anywhere about that - not in QRs or as far as I know any other regulations. However it is certainly a tradition, and you'd have to ask someone like Johnson Beharry VC if it is still commonly observed. I believe a similar tradition exists in US forces with the holders of the Medal of Honor.
Never had the good fortune to meet a VC holder when I was serving (or since, for that matter) so I never had the opportunity to observe the custom.