config.ts

import { OpaqueToken } from 'angular2/core';

export interface IConfig {
  fbRef: string
};

export const CONFIG = {
  fbRef: ""
};

export const IConfig = new OpaqueToken('app.config');

FirebaseService.ts

import { Inject, Injectable, OpaqueToken } from 'angular2/core';
import * as Firebase from 'firebase';
import { IConfig } from '../lib/config';

export interface IFirebaseService {
  ref: Firebase;
}

export const IFirebaseService = new OpaqueToken('FirebaseService');

@Injectable()
export class FirebaseService {
  ref: Firebase;

  constructor (@Inject(IConfig) _config:IConfig) {
    this.ref = new Firebase(_config.fbRef);
  }
}

SchedulerService.ts

import { Inject, Injectable } from 'angular2/core';
import { IFirebaseService } from '../lib/firebase.service';

@Injectable()
export class SchedulerService {
  private schedulesRef:Firebase;

  constructor(@Inject(IFirebaseService) fbService:IFirebaseService) {
    this.schedulesRef = fbService.ref.child('schedules');
  }
}