There is an example. See the
README which cites how to point to a script, also citing the default script that should be located in: /usr/share/udhcpc/default.script.
Have you looked at their default script and viewed this README to understand the options you have where you can then next determine what configuration best works for your situation?
I think the easiest way to set it up is to start with their defaults, then determine if you need any customized settings.
