Include files from other folder outside of angular project

Question

In angular-cli.json , I am trying to set some environments file which won't be a part of the project . The root is set to src which I want to keep intact but in environments config I want something like this to work

"environments": {
        "dev": "environments/environment.ts",
        "prod": "environments/environment.prod.ts",
        "qa": "environments/environment.qa.ts",
        "stage":"environments/environment.stage.ts",
        "cust1-dev": 
"../CustomerConfiguration/Cust/UI/src/environments/environment.ts",     
}

Is this possible ? Currently This doesnt work.