An alternate recipe gleaned from Chowhound.

25 green walnuts
3 cloves
1 stick cinnamon
peel of 1 lemon (yellow part only; the white pith is too bitter)
1.25 liter of vodka, 100 proof
3 cups sugar
1?4 liter of cheap sparkling wine
1. Soak the walnuts overnight to draw out any worms and other impurities.
2. Quarter them and put them into a large jar with all other ingredients. Place in a sunny spot, sealed, for at least 40 days; 2 months is better. Shake every few days.
3. Strain and bottle the liquid. Put a few bottles away to age two to three years.