How do I configure dynamic DNS when my router does not support it?
ddclient is what I use on my Linux boxes. Works really well.

You can find instructions details here: http://sourceforge.net/apps/trac/ddclient

I think all you would need to do to get ddclient to run is to a @reboot line to your crontab and you’re set. 

crontab -e


then add this line:

@reboot /usr/sbin/ddclient -daemon 300 -syslog