Virtualmin and dDNS

I am thinking of changing over to Nextlight (Longmont, CO), but unfortunately they will not sell an IP address, except to a registered business.

I've looked into using dDNS and there are a couple of options that I can get working for my web / email server.

The problem though is Virtualmin, or I'm missing something.

Nextlight will hand my server an ip address via dhcp, but I can not find a way of getting Virtualmin to see an IP change on my external nic and then do an update.

Have I missed something, I'm sure I have.

Nigel.