All I can offer on obtaining the Keesha BJ at the moment (due to time) is to search the *.rpy files with something like NotePad++ for "keeshabj" and work back from there.I think you have to make sure to mention to her that "she owes you" now for the bj tape BEFORE giving it to her to set the variable. Because I also was like nah I don't wanna sound greedy and thought she'll appreciate it but had to find out it doesn't work like that with people like Keesha. So tell her that you want sth in change and a couple of days later when you meet her in Skyebar be ready to be "blown" away I don't know the day you have to go back to but I'm quite certain P4cc3r5 knows exactly to the detail what you have to do
Taking a quick look at it the trigger is on Day 76 when you give her the Rebecca/Boris photos or the Rebecca BJ USB stick.