Simon
The offshore world used to have such a thing as an instrument qualified but not rated co-pilot. These qualifications were given by the offshore company so long as you passed an instument base check (IBC). It was only valid for that company and allowed 2 crew IFR so long as the commander had an IR. Once the co-pilot had enough time under his belt he was trained for and then sat the IRT with the CAA and became a fully fledged pilot with an IR. Sadly the regulators did away with this system and all 2 crew IFR helicopters in the UK have to be crewed with 2 pilots each with an IR.
So don't hold your breath for a change in the system.
HF