Provided that you have specified different firewalls in /usr/local/sbin/ (based on customized versions of a basic IPFW ruleset) you can easily switch between different firewall settings from the command line.

First create the different firewall settings & files:

# find /usr/local/sbin -name "*firewall"

/usr/local/sbin/rc.firewall         # default firewall setting
/usr/local/sbin/rc-ftp.firewall     # FTP firewall setting (enable FTP rules)
/usr/local/sbin/rc-ssh.firewall     # SSH firewall setting (enable SSH rules)
/usr/local/sbin/rc-SL.firewall      # Second Life firewall setting (enable Second Life rules)
/usr/local/sbin/rc-r.firewall       # restrictive firewall setting, cf. http://prefetch.net/blog/index.php/2006/08/13/locking-down-the-os-x-firewall/

Then:

# $ cat $HOME/.bash_login

function fwdef() { /usr/bin/sudo  /usr/local/sbin/rc.firewall; }     
function fwftp() { /usr/bin/sudo  /usr/local/sbin/rc-ftp.firewall; } 
function fwssh() { /usr/bin/sudo  /usr/local/sbin/rc-ssh.firewall; } 
function fwsl() { /usr/bin/sudo  /usr/local/sbin/rc-SL.firewall; }   
function fwr() { /usr/bin/sudo  /usr/local/sbin/rc-r.firewall; }     

#----------------

# in Terminal.app

source $HOME/.bash_login 
fwdef
fwftp
fwssh
fwsl
fwr