app.js

var app = angular.module('Myapp' [

])
.factory ('Foo' , function(MyServiceThatUsesHTTP){
  var userDetails = {};
  
  userDetails.setToken(aToken){
    this.token = aToken;
  }
  
  userDetails.doSomething() = function(){
    MyServiceThatUsesHTTP.meh();
  };
  
})
.run(['', function(){
  //Here there by dragons
}])
.config('', function(){
  //overwite the response interceptor here
  $httpProvider.reponseInterceptors.push([
    'Foo', function(Foo){  /** PROBLEM because of this */
      //...
      if(reponse.status ===401 && .......){
        //We need to get a new token and save it to our userDetails
        $injector.get('$http').jsonp('/my_auth').then(function(response){
          if(response){
           Foo.setToken(response.mytoken); /** PROBLEM because of this */
          }
        });
        ....
      }
      ....
    }])
});