Brew the coffee very strong, and allow it to sit on the hotplate until about half of it has evaporated. If you do not have an automatic coffee maker, this can be done over the stove, but it is critically important to never let the coffee ever come near a simmer. if it does, it has burned, and you can basically toss it.
After reducing by half add the sugar and vanilla bean, and let it sit for about an hour, until it has cooled to room temp. You may want to only add about half the sugar you think you will need, and add more, if it is needed, after it has aged.
Add the vodka, brandy, and salt, and stir well, and let it sit for another hour. Stir it briskly again, and put it in a glass bottle. I have found that, depending on the amount of sugar used, you should be able to fit it into a gallon bottle. Do not, however, put it in a bottle that is too big, as many of the volatile oils from the coffee and vanilla will evaporate, instead of suffusing into the Kahlua.
Allow it to sit for about 2-3 months, and sample it. It is at this point you will want to add more sugar, if it is needed. If it tastes good, it is ready, if it needs more sugar, give it another week.
Some variations: Flavored coffee works fairly well, and I have gotten different tastes with different sugars (white, cane, brown, tobago, corn syrup, and molasses are what I have tried). I have also used non dairy creamers, in different flavors, successfully (I didn't like them, but many of my friends did)