Configure DPI

I'm trying to configure the DPI option but can't find any option to do so.
Is there a way to add your own parameters by overriding something?
Currently PdfConfig.toParameters is hardcoded so I can't change what parameters are used.
Maybe adding aval custom: Seq[String] = Seq() that can be overridden in the PdfConfig?

For the DPI option, I think you can use the zoom parameter (e.g., zoom := 4)