Changing the FastBoot runtime environment

I've got a question about how to best load an Ember application built from Ember CLI into FastBoot for [ember-cli-fastboot-testing](https://github.com/embermap/ember-cli-fastboot-testing)

I have an Ember application that's built using ember-cli, so it's build time environment is `development`. When I load that dist path into `new FastBoot()` it uses the the application's config environment of `development`, which makes sense!

However, I'm wondering if I can take that same build and load it into FastBoot with a run time environment of `test`. I guess this question boils down to: Do I have the ability to tell FastBoot to use a different run time environment + config from what the app was built with?

What I'm trying to accomplish: I want fastboot-testing to piggy back off of the dist built by ember-cli-fastboot, but when it loads that dist I want it to use a runtime env of `test`.