LCDd is the display server, sdeclcd is the display driver for firebox display & kbd.
messages are generated by lcdproc which creates the screens.
if you want to customize displays, you may modify lcdproc and compile it on a freebsd machine.
you will find souces package and compiling instructions on lcdproc source forge page (ver 0.5.3) http://sourceforge.net/projects/lcdproc/
, the web site is not fully updated.
i did compile it under freebsd to get the latest version, compiling is easy, if you do not make typing errors...
LCDd can accept simultaneous connections, so you can also use others programs to create dispalys, and you can use lcdexec to create menus.
lcdproc is flexible in the way you can select different screens which will be displayed one by one, and with lcdexec you can create menus with (limited) actions.
but screens are pre-programmed.
another alternative is lcd4linux, which allows to customize your screen, but you can have only one screen.
another nice feature is the availability to display 2 graphs in one line, there is a complex routine to allow that with only 8 graphic chars, this is remarquable.http://ssl.bulix.org/projects/lcd4linux/
unfortunetely, it does not compile natively under freebsd, i did it, but it was extremely long to setup, and for installing it it on pfsense, you will have to add manually a lot of libraries.