Simplest option - Put all of the ingredients together in a large glass container (plastic will impart a flavour due to the slightly raised alcohol levels) and try to ensure that there is no air gap (adjust your proportions slightly if necessary).
Alternatively - If you are concerned about the link to cyanide, then bring the wine to a simmer, add the leaves, and remove from heat.
Allow the mixture to cool before adding the brandy or neutral spirit, the sugar will dissolve easily in the warm wine. Allow to cool before bottling. Into a large glass container. Try to ensure that there is no air gap (adjust your proportions slightly if necessary).
Allow the mix to infuse in a cool dark place, not a fridge as this will slow the rate of infusion, for anything between two weeks to 3 months. During this time, the container should be rolled to re-submerge any leaves at the top on a weekly basis, otherwise mould may form. The heat infused wine will require less time and may be ready after a week.
Once you have decided that the flavour is strong enough, drain the wine from the leaves without crushing them (or it will become bitter) and bottle into glass.
The wine will continue to improve in the bottle for some time. Open bottles are protected by the raised levels of alcohol and so do not spoil quickly.