What methods have you tried to emulate extraversion? A friend of mine used improv and acting to help them "act" more extroverted, YMMV. Me, I'm still emulating too.
Various combinations of medications, prescribed and self-selected, have failed. It wasn't exhaustive exactly but I would say that it was a good survey of the field.
Memorizing quite a lot of detail about people helps in making you seem engaged, but there's a fine line (past a certain point, if you confess to remembering whatever counts as "too much," it becomes "creepy"), and it still hasn't affected the base.
Self-talk, acting, improv -- it increases the fidelity of the emulation but it's still emulation.
At the end of the day, other people say "hello" and I have failed the initiative check, and am pondering what exactly do I say back to them, and they've already gone by.
A remarkably stable trait for me.