Ionic 2 show login page over slide menu app - authentication

Question

Q) How to I show a login page over the top of my standard slide menu app in Ionic 2?
My slide menu app is up and running, I just need that initial login page setup correctly.
Things I know:
How to show a modal page with nav.present().
How to dismiss a modal page.
Things I DON'T know:
Where to instantiate + show this page
How to have it accessible from any current page (i.e. if the user is logged out)
Note: this is for Ionic 2, not 1. I know there are many examples of this in Ionic 1, but they're not applicable thanks.
Any ideas? Thanks.

Answer 1

Solved: Using event listeners as follows:
1.) I have added a LoginPage to my app.ts:
import {Events} from 'ionic-framework/ionic';
import {LoginPage} from './pages/login/login';
Then, I made it the rootPage:
class MyApp {
rootPage: Type = LoginPage;
2.) Then, I register some listeners:
ngOnInit() {
this.subscribeToEvents();
}
ngOnDestroy() {
this.unsubscribeToEvents();
}
subscribeToEvents() {
this._events.subscribe('login:success', () => {
this.getNav().setRoot(TodosPage);
});
this._events.subscribe('logout:success', () => {
this.getNav().setRoot(LoginPage);
});
}
unsubscribeToEvents() {
this._events.unsubscribe('login:success', null);
this._events.unsubscribe('logout:success', null);
}
getNav() {
return this.app.getComponent('nav');
}
3.) Then, in my LoginPage:
<button full (click)="login()">Login</button>
login() {
// Do some auth here first...
this._events.publish("login:success", null);
}