All I do to make the 777 cold and dark is -

1) Load the 777-200 Cleared for takeoff (KSEA).FLT
2) Shut the engines down, and turn everything off (on the OH panel) to put it in a cold and dark state
3) Move the 777 to a Gate B11 (Heavy) at KSEA
4) Save it. I named mine 777-200 Cold-n-Dark (KSEA)

After I have saved the flight, I check to see that the saved FLT has all the extra [CaptainSim] entries (sample below) at the bottom of the file. That way, I know it should be okay to use.

*[CaptainSim] sample:

[CaptainSim]
PF000=1
PF001=4
PF002=1.624022
PF003=100.882652
PF004=1
PF005=15.000000
PF006=0
PF007=8.000000
PF008=16.000000
PF009=5
PF010=1
PF011=28.000000
PF012=1
PF013=6.050000

*Note: There are hundreds of these lines of entries below [CaptainSim] in the aircraft.cfg!