Yes, I'm an international member. Those tickets can only be purchased by phone. And it's pretty difficult. What you need, basically, is some luck.
First of all: depending on what Juve decide, either only international members are allowed to contact the call center (as happened for the Inter game, for example) which should make things easier or Italians can contact them as well as is most often the case.
And equally important, if possible, make sure you're able to call through various operators. I literally tried 100s of times with the fixed house phone, the fixed one at work & my cell without getting through once. Then tried a different cell with a different operator & got through within the hour. And I've heard the same story from different people, both based in Italy & abroad.
Personally, I most likely won't renew my membership next year if they don't change the way we can purchase tickets.
I don't mind paying for the membership, but the current system is just retarded.
I promised myself to have one every day, but I failed. Didn't get one on the day of the match