Ideally one needs an assistant, but it can be done on one's own.
Most important is you need to remove the fan if you are still running the mechanical one. You need the space to separate engine and gearbox. The engine does come out without the gearbox, but you have to twist it slightly, putting the thermostat area to the left hand side of the car (passenger side in the UK).
Truthfully - I can't see that you'd get the gearbox out attached to the engine as there is a cross-member in the way.
Only time I've fitted an engine without a hoist was at rebuild time. It may be possible to remove engine from below, but it will be tricky as the chassis will get in the way.
In the UK, hoist hire is expensive, I've got a proper hoist and as it has been used 3 times for a 4/4, two weekends of messing sorting out the three wheeler and lent to a friend with a MG Midget, it has more than paid for itself.
