Found a recipe for Yakka on the SSDC blog.
For one bin of yakka:
1 bin (buy a new one)
1 stirring stick (a metre long ruler is fine. Or a yard long one for American types).
6, 7 or 8 litre bottles of vodka
1 litre bottle of lime cordial
1 kilogram of sugar
As many lemons and limes as you can get (cut into halfs)
A big bag of ice
1) 24 hours before you want to drink the yakka. Pour one of the bottles of vodka into the bottom of the bin. Pour about a 6th of the sugar in and a 6th of the lime cordial. Chuck some lemons and limes in as well. You can if you wish squeeze the limes and lemons (I normally don't as the limes/lemons are crucial to the flavour and fermentation). Stir vigorously.
2) Do this with each bottle of vodka. Each time put some of the sugar, lime cordial and fruit in. The reason for doing it in dribs and drabs is so that the sugar, lime cordial and fruit are equally dispersed. Stir throughout this process.
3) When all the ingredients are in, throw in some of the ice (not very much - a couple of handfuls maybe).
4) Store in a cool place. Stir vigorously every 4-6 hours (more often if you can).
5) Just before serving throw lots of ice in!
6) Serve to a glut of people
Obviously, if you want more bins you just go through the same process numerous times. I’ve made the yakka with varying amounts of booze. The first time I made it I used 6 x 1.5 litre bottles (so 9 litres) but it was fine. I’d recommend 6 or 7 litres of vodka. Lots of fruit and lots of ice (last minute) are crucial. One, the ice stops people necking what is effectively super-strength straight vodka. Two, the more fruit, the less alcoholly the taste which is good and bad!
There is a school of thought that says if you make the yakka 48 hours before it is even better. I'm not convinced. 24 hours makes good yakka and is, self-evidently, less time consuming. Some people will say that they have left the yakka for a month to ferment... again, I suppose if you can be bothered that must be great. However, rudimentary science suggests that the longer the lemons and limes are in the juice, the more bitter the taste willl become. 24 hours is just fine.
There are some interesting developments in South Africa using gin and cane rather than vodka. I'm sure both work admirably. Maybe someone could invent a yakkacello sort of liquor? Any white spirit (tequilla?) in principle should work. However, cheap Union vodka is the classic taste.