(a) the chasam sofer chidush that you quote is not in the chidushim on lulav hagozel perhaps you gave the wrong location.
(b) also what would be the din if a yisroel brought a lulav or shofar from chutz litchum would he be yotze or would it be a mitzvah haboh beaveirah?
mendy kaplowitz, bklyn,ny usa
(a) If you are referring to the Derashah of the Chasam Sofer regarding the Esrog Kushi, you will find it in the TESHUVOS CHASAM SOFER, at the end of Chelek Yoreh De'ah, where most printings include the Chasam Sofer's Chidushim on Perek Lulav ha'Gazul. (In the newest printings of his Chidushim on the Masechtos, these Chidushim on Lulav ha'Gazul are included.)
(b) Good question. It does not seem that the principle of Mitzvah ha'Ba'ah b'Aveirah applies, because the Mitzvah is not being done after the Aveirah has passed (see our Insights to Sukah 30:1 for the different opinions of when Mitzvah ha'Ba'ah b'Aveirah applies). Also, my brother pointed out that the Acharonim prove from a Yerushalmi (in Shabbos and Pesachim, regarding one who rents "Keri'ah" on a deceased relative on Shabbos) that the principle of Mitzvah ha'Ba'ah b'Aveirah doesn't apply to the Aveirah of Chilul Shabbos.
However, there might be another problem. Assuming that he brought the Lulav in such a way that he was not Yotzei the Mitzvah the moment that he picked it up, do we apply the Isur d'Rabanan which prohibits benefitting from an act which was done on Shabbos or Yom Tov which was forbidden to be done? It would seem that in this case we can say that "Mitzvos Lav le'Hanos Nitnu." G-d willing we will look into this question and get back to you.
Be well,
-Mordecai Korneld