Turkeyslapper - for training we practise the IFR procedure a lot and the crew will have the goggles on but with the HP flying on instruments (the NVGs can be flipped up and down on their hinged mount). Our radar allows us to fly below Safety Alt, IMC over the water as long as we don't overfly radar contacts below 1000'.
During the letdown, the NHP (on NVG) would advise visual when he can see the surface and the HP would either continue to the next step height (500' or 200') and then fly on NVG if the conditions were suitable or elect to stay on instruments all the way to the hover. Once the HP is on NVG, the FCS/FPC (autopilot bits) are used to assist, if required, the letdown to the vessel but if conditions are good there is no reason why the HP can't make a visual approach to the boat on NVG.
At all stages we fly with either bar alt or rad hold in for height protection and regardless of IFR or NVG flight use the same check calls during the letdown. We set Bar alts to agree with rad alts at 500' and again at 200' - the Mk 3 engage rad alt at 200', the 3A's have it available (and on manoeuvre) anywhere below 1000'.
If the weather permits, there is no problem with getting airborne, coasting out and letting down on NVG and in this case the pilots are responsible for collision avoidance rather than the radar operator but, since you are effectively flying VFR, this is not a problem.
Once alongside the vessel, the HP will flip up his gogles and revert to white light for the recce and winching whilst the NHP will normally remain on NVG for lookout and in case he needs to fly the aircraft following an engine failure.