Hey Deckman, I haven't had any luck with a starter recipe for viili yet, but I did find a recipe for sima, identified as a Finnish citrus wine. Since Finland isn't famous for it's citrus industry, I'd be a bit skeptical, but I know the author of the pamphlet, and she does her academic homework before she publishes anything. So, from a pamphlet entitled Beverages fro the Current Middle Ages: Techniques and Recipes for the manufacture of Medieval Drinks, by Jane Sibley:
2 large lemons (or one lemon and one orange), 1/2 cup granulated sugar, 1/2 cup brown sugar, five quarts boiling water, 1/8 teaspoon yeast, five teaspoons sugar, fifteen raisins.

Carefully peel the fruit. Carefully remove the white membrane and discard it. Slice the fruit very thinly and place in a 6 to 8 quart enamel or stainless steel bowl, along with the fruit skins and the sugar (1/2 cup each brown and white, that is). Pour the boiling water into the bowl, stir, and let cool until lukewarm. Then add the yeast and allow to ferment, uncovered, at room temperature for about twelve hours. To bottle, use 5 one-quart bottles (I use champagne bottles). Place one teaspoon sugar and three raisins in each bottle, then strain the sima into the bottle through a sieve. Cap the bottles tightly, and let stand at room temperature for one or two days, or until the raisins rise to the surface. Chill the sealed bottles until ready to serve.
If you aren't familiar with basic brewing techniques, the only thing you really need to know is that all of the equipment, bottles, etc. you use has to be scrupulously clean, with any of the cleaning agents (soap, bleach) removed as thoroughly as any dirt. Have fun, Mary