The gemara about yilbash shechorim is in three places, Kidushin 40a, Moed Katan 17a, and Chagiga 16a.
Tosphos in chagiga and kidushin bring a pshat from R’ Chananel that doing those various things will break his yetzer and he won’t end up sinning, but Tosphos in chagiga argues that the gemara implies otherwise. Tosphos in eiruvin 41b also shares this view. The gemara there is about the three things that force a person to sin, and tosphos adds the fourth one based on the gemara above.
Perhaps what R’ Chananel meant is that its not a free heter to do some trick and live it up as you please. To this R’ Chananel says that the objective is to break the yetzer (by mourning ones sorry state) so that he will eventually get the sin out of his system.