Custom DynDNS update frequency

[korhojoa]

I am using a custom dyndns due to my provider (dy.fi) not being in the default list. They have a required check-in frequency of 7 days, so pfSense does not satisfy that currently.
How do I go about changing the frequency so that my domains aren't suddenly pointed to nothing?
Would adding a update frequency-option in the webgui be difficult?