You need root privileges, or at least be in the "tty" group, because
it reads /dev/vcsN and writes /dev/ttyN.
It follows the same idea as WinVNC, x11vnc or OSXvnc, i.e. it
takes an existing desktop and exports it via RFB (VNC), just that
LinuxVNC exports text.
If you want to export another tty, specify it as 'tty_number'.
You can also pass VNC options to tune what encodings are used for the VNC
session. You can read x11vnc man page for more information on this.