How to replace one ability score with another in a template?

[Aril]

I'm trying to set up the "Fey-Touched" template from Wrath of the River King (Kobold Press).

It's largely intended to create talking animals.

The template is supposed to set the INT score of any animal, magical beast or vermin to which it is applied to INT 10, instead of whatever score they originally had.

Is there a way to do that? I know the tools allow me to add a bonus, so in theory I could add +8 to INT and call it a day. But that wouldn't work for Vermin, who have INT 0, or for Magical Beasts who can have INT of up to 4 to be eligible for the template.