The principle involved here is that the gear lever won't want to move whilst the gearbox is under load - ie acceleration of deceleration.
The way to rake the load off the gearbox on up shifts is to roll the throttle off a touch quickly and then lift the gear lever - just as you would roll off with a clutched changed (the clutch is just a mechanism to disconnect the gearbox from the crankshaft driving force anyway and take the load off).
On downshifts, "blipping" the throttle also reduces the load through the gearbox and makes clutch less shifts easier and smoother.
In the late '80's I had a Ford Fiesta which had a plastic toothed ratchet on the top of the clutch pedal which pulled the clutch cable - and it wore out regularly, leaving me with no clutch. As a result I made half a dozen trips from Liverpool to Newcastle (or back), without a clutch - and once I'd mastered clutch less changes, out of necessity (matching RPM's to speeds in gears), I could change as smoothly without a clutch as with one.
Moving off from a standstill was trickier - into neutral, stop, engine off, into 1st (or 2nd), turn the key in the ignition to engage the starter and as the car jumps forward, hit the gas and let go of the key - then into 2nd ASAP and proceed through the gears. It also made reading the road and reading traffic a real skill, so you try to always keep rolling and avoid harsh acceleration or deceleration.
Great fun - and a surprisingly effective way to drive economically.
