Hello Mozzie,
Is your steering wheel on the right with your '41?
Glenn's lengthy note explains the procedure really well, and Fred's adds some to what I think I understand. I believe the principle is simply that without synchromesh, you have to get the flywheel on the motor going at about the right speed to make the shift to the transmission without grinding the gears. You can do it just with the gas pedal like Fred did, or you can double clutch or you can do it slowly. Their is a problem with the latter though. If you shift into 3rd from 2nd at the same wheel speed and the same way every time, you can learn how slow is just right. But then the next time you go faster in 2nd before shifting than you usually do, you'll find the same slow speed won't work for you because the transmission is going faster than you are used to. In this situation you have to be slower yet to make the shift. Make sense?
I still don't know what all is going on in the gearbox when you let up on the clutch with the transmission in neutral and your foot off the gas so that the engine is slowing down. I don't see how that makes the shifting into the next gear any smoother. Letting the clutch out in neutral must match the front gear in the transmission to the engine speed, but why does that help mesh it to the rear gear?