For educational purposes (not that anyone should care the motivations behind such an exercise) I'd like to write a program that can read/write to/from alternate tty/pty's. I've read papers (from the 1990's) but can't employ the implementation they use, on modern UNIXes.

I was hoping that someone had researched into this in the past, or at least, read documentation pertaining to it, that they could provide.

I also wonder if (considering the fact that Linux doesn't have STREAMs) if this exercise must be done via a loadable kernel module?

I have many questions and probably a misunderstanding of some of the fundamental ideologies that allow such objectives to be put in place, could someone help? :)