Formz and formit hooks - where to define?

I'm using silentworks excellent Formz plugin. I'd like to execute a bunch of other stuff (more specifically adding data to a custom DB table http://blog.kingori.co/2012/02/how-to-save-formit-data-to-db-in-modx/ ) using a formit hook but I can't see where I specify the hook as it's all done using a custom template variable type.

Can anyone push me in the right direction as to where I would put extra parameters in the formit call to execute a hook?

You'd likely want to extend the "Formz" output type to allow for custom variables. Now, HOW to do that I'm not sure. I think the files you want are in: /core/components/formz/templates/elements/tv/renders though. Sorry i couldn't be more help!

If you only have 1 form, or want your changes to be applied to ALL, you COULD just edit the output chunk directly: /core/components/formz/elements/chunks/formtpl.chunk.tpl