Dynamically set default_value in the ProductCategoryInput widget

Hi

I understand that seemingly the only way that one can dynamically set the default_value of the ProductCategoryInput widget would be to extend the OOTB widget.

Understandibly, learning the in's and out's of extending widgets is in order, but like all real world scenarios, a solution is required sooner rather than later.

I am getting the ID of the product (Incident.Product) via a custom search. I am wondering if someone has any tips / direction / sample code that could be adapted to allow for dynamically setting this once the product is selected from the custom search.