Specify file of stack params when deploy

I am using stack parameters in my cloudformation. I need to set these when I deploy. The normal AWS cli stack create/update lets you specify a file of params. I need to get these somehow to serverless to do for me. I have a severless plugin I am using for my own project to trick out serverless. I’d be OK to inject these params somewhere that serverless can find them and use them. I’ll even modify serverless if I have to, though I really don’t want to. Ideass?