For my ORD-NRT-BKK trips, I do the following:
1. Sleep in as late as possible the day before the flight.
2. Stay up all night the night before the flight
3. Take 1-2 Melatonin tablets with the first meal
4. Sleep the rest of the flight, oftentimes skipping the 2nd meal. Having a good neck pillow really helps with this, as does an upgrade to C.
5. Take a shower at the RCC in NRT (very important!)
6. Do NOT sleep NRT-BKK
7. Arrive at BKK very late at night BKK time, so take more Melatonin and sleep immediately.
Voila, instantly adjusted to BKK time.
For those of you who are opposed to popping pills, Melatonin is a naturally-occurring hormone and an extremely strong anti-oxidant as well! So you can safely take it every night without the addictive side effects of pharmaceutical sleeping pills.