How to set environment variables in sbt shell?

I see that it's possible to set JVM parameters in Preferences > Build Tools > sbt. However, I don't think it's possible to set OS-level environment variables via such JVM parameters. Is there any way to do this?

So far, I've been using a regular Terminal window where I manually `EXPORT` the desired env var and then run `sbt` from there rather than from the built-in sbt shell window.

My specific use case is to set configuration values via env vars https://github.com/lightbend/config#optional-system-or-env-variable-overrides

Thank you