If you are using syscons (the default console driver) in FreeBSD 2.2.7-RELEASE or later, build and install a new kernel with the line
in the configuration file. If you use the PCVT console driver in FreeBSD 2.2.5-RELEASE or later, use the following kernel configuration line instead:
For older versions of FreeBSD, edit the keymap you are using for the console and replace the boot keywords with nop. The default keymap is /usr/share/syscons/keymaps/us.iso.kbd. You may have to instruct /etc/rc.conf to load this keymap explicitly for the change to take effect. Of course if you are using an alternate keymap for your country, you should edit that one instead.