Alton Brown's recipe is great. Also, I made a great one with cherries, pecans, and amaretto. BTW, I did the same exact thing this summer with a fruitcake to keep as the top tier.
A few tips from my research:
The fruit cake should be made about three months ahead of time. Then it should be brushed with alcohol every week for a few months and kept wrapped in a cloth in a tin. The harshness of the alcohol dissipates as the flavor of the cake mellows.
A few weeks before the wedding, it should be covered with marzipan. This should then sit to dry for at least a week to dry out.
Then it can be covered in fondant or royal icing. Royal is more traditional and will serve to help keep the cake preserved for a longer period.
Some of our European friends can enlighten us, but it is my understanding that the royal icing is meant to break off at the time of cutting like hunks of candy. Cutting the cake is not a gentle process.
