Cant tell you as i am not from around there, but i can give you a simple recipie that is not illegal.
1 liter of Vodka
250gms white sugar
zest from about 6 lemons.
peel the zest from the lemons into a large jar, pour in the vodka and let sit for 10 days
add water and sugar and decant into bottles.
Note the ABV value for this is lower than true Limoncello so it tends to freeze in the freezer.