I haven't tried it yet, but I am sure you could leave out the lemon and just use the rest as a base and then add your own mix in's or substitute another flavor for the lemon.
1 c. sugar
3 eggs
1 c. milk*
1 1/2 tsp. lemon zest
1/2 c. fresh lemon juice
1 tsp. vanilla
1 1/2 c. heavy cream
Combine sugar, eggs, milk, lemon zest, and lemon juice in a saucepan. Cook slowly over medium heat until it just simmers. Remove from heat and add the vanilla. Strain and cool in the fridge overnight.
Remove from the fridge, add the cream and pour into an ice cream maker.
*you can substitute evaporated milk or some sweetened condensed milk. We like 1/2 c. milk and 1/2 c. sweetened condensed milk.
from Lee Stott