The scene with Katarina you get by working at the tavern, for the other one you have to talk with Jinx (click directly on her).
Started the game up again to check:
For the Kat scene:
- Work as a waitress
- You have to get all the drinks right (The patrons will grope more and more)
- Then select "Stay after closing the bar."
For the Ahri/Sona scene:
- Go to the sex shop
- Select "Buy sex toys."
- When the toy selection screen is up, click on Jinx
- For me the choice is "Backroom..." but it could be different for the first time, I don't remember.
That's so weird, I haven't ever gotten the "stay after closing the bar" option, I get paid after a perfect night, Kat says it was hot and then I call it a night immediately. I've already gotten the whole Kat x Janna stuff unlocked, and I have the two toys that Jinx offers. Clicking on Jinx hasn't gotten me anything either. Hrm. I'll keep looking but I appreciate the help.