Claude,
This is clearly a question for "people who know stuff", whom I believe can be found over in the new BODA club
I have never done this job, so I can't provide a blow by blow description and I don't know for sure whether you need to remove the tranny tunnel and seats.
It's unfortunate that you didn't post your question yesterday when I had my 411 on axle stands - I could have had a look. That said, when I bought my 411 I had the tranny reconditioned and I know they didn't touch the tranny tunnel or the seats to get it out.
As for the flywheel bolts that you refer to, these are probably the four bolts which fix the torque converter to the flexplate, which in turn is connected to the end of the crankshaft (there isn't a flywheel per se, just a starter ring on the torque converter). However, if you leave the flexplate bolts in place the transmission spline should just slide out of the torque converter (with some very gentle wiggling), which would leave the torque converter connected to the engine.
If you do end up disconnecting the flex plate from the torque converter, make sure you mark one ear of the flexplate, along with the torque converter body so it's easy to reassemble the same way it came off.
The usual caveats and disclaimers apply
Please let us know how you get on.