What does that mean - they say "until the mixture becomes an easy workable smooth dough" - but how do you know if you haven't added enough or added too much?
Do you have a better recipe?
Biscuits require 3:2:1 flour:liquid:fat. Cookies are 1:2:3 sugar:fat:flour. (from Michael Ruhlman's book Ratio)
I'm guessing based on the description you'll fall somewhere in the crack between there around 5 cups flour. However, you will simply need to develop the dough maker's intuition by trial and error. I'm guessing a strict cookie dough ratio will be too inelastic, but I've never had these "cookies"before, nor have I made any with wine in them. All the same I think that you'll be toward the cookie end of that ratio spectrum (biscuit v. cookie). Just be patient adding tablespoon by tablespoon.