The Star Alliance Lounge at T1, if I remember correctly, is in the main 'cylinder' on the 10th level. Once you deplane at one of the satellites, you take the underground moving walkway to the main 'cylinder' bits and it dumps you in the duty free shopping area (4th level?). Whether you turn left or right, you'll eventually run into immigration desks... but in between, by the Hermes shop, there are elevators that take you up to the lounges. As security occurs at the satellite boarding area, process-wise this puts you sort-of-airside, but not yet entered the country. It seems feasible that you could head up to the lounge, and then when finished you go back downstairs and do immigration and hit baggage claim and transportation. I could be wrong... am I?