bash: take exclusive control of the console/tty

I have a script which implements a simple menu using dialog (an ncurses app for generating TUI widgets). This runs immediately after boot on an Arch-based system. The dialog script works when standalone, but there's a problem when it's run after boot. The boot process writes some delayed output to the console ("Starting network manager script dispatcher service", and possibly a later timeout), and this writes over the menu, and messes up the tty modes. I can fix the tty mode (stty sane), but I also need to stop the text reaching the console. Is there some way I can dump any kernel console output from the script?