Offer them at NRT, walk to lounge and escort from lounge onboard the plane. Security is special for the ANA Suites Checkin (which LH F, LX F, and HONs departing on OS, LX and LH can use and of course ANA F pax), but passport control is with the ordinary passengeres. I have heard some can clear passport control faster, but my escort didn't attempt when I used the service last August. It seems like that LX offers this service for all F pax at NRT, while LH offers it for HONs only. When I checked in for my LH flight last Monday there was no escort service at NRT.