You can do CollegeCams streams with both NPCs and The E-Girl!
For regular NPCs: they have to be your sexual partner (don't have to be romantic partner, but can be) and have a good relationship
with you + the Exhibitionist trait. Then on the screen where you
pick your outfit before going live on CollegeCams there should be an option to invite them. Note that your own
Exhibitionism skill has to be at least 6 or 7 to do anything with them, tho.
For the E-Girl: there is a whole quest where, at the end of it, you
can stream on CollegeCams with her every Saturday. You have to join the Esports team, be a Niche streamer, AND a CollegeCams streamer. Eventually she will approach you about
streaming together, which unlocks doing Niche streams with her on
Saturdays. Keep doing that and with high enough skills (Charisma OR
Exhibitionism OR Assertiveness, don't need all 3) you will eventually persuade her to join you on CollegeCams.