I've packed and unpacked my Thorn Nomad MK1 rohloff S&S quite a few times over the past few years on my tour.
I've always used boxes from supermarkets or anything I could find.
The airlines have always taken them but they have insisted they go through the over size baggage counter.
That has not cost me any more money, only the standard weight cost I would have paid if it was a suitcase.
I do always make sure I find out the max dimensions before flying and have that info in an email.
The biggest part of the box will be depending on your fork steerer. Mine is uncut so always adds a bit of extra size.
On my last flight from Kuala Lumpur to Gatwick with Vietnam airlines I used the cardboard box from a pair of loudspeakers.
This was within the airlines maximum dimensions.
Minimum 1 hour to disassemble.
Unclip brake cables from calliper, unclip rohloff from wheel/frame, remove seat and saddle, remove racks, remove mudguards, remove wheels,let down tires, remove forks, disassemble frame, leave bars and cables attached.
I would pack a wheel on each side of the box with the parts of the frame between. The pedals stayed attached and went through the spokes so as not to move around. Both mudguards would sit on one wheel and the rear rack would sit on top of the other wheel. Everything else would slot in somewhere in-between.
I would pack out the spindles with old clothes or polystyrene.
Most of my bike is still in the box. I will go and take some photos and measurements tomorrow in better light and post them up here.
The main things to note are
Uncut steerer
Racks and
Mudguards
all need to come off to pack down small. This is what takes the time. If the bike is naked it takes a few minutes.
As for flying, try to use an airline that will actually take bicycles for a flat extra fee. This works out a hell of lot cheaper than paying excess luggage rates at $100 per kg .
I posted so much stuff home from my tour to avoid excess fees. Every single Postoffice got my parcels back to the UK in the time stated