I don't know, if my answer fits to situation Facebook has over two years ago (when this question was originally asked), but today this seems to be way simpler.
Once you create a Facebook Page and login with your original account, you simply select
Use Facebook as [page name] from Facebook's gear icon and then... you go, browsing Facebook and liking, whatever you... like. Any time you like something, it will marked as your Page's like, not your own account. You will even see a cleare message in your Facebook toolbar:
You are posting, commenting and liking as [profile name] — Change to [page name] and vice-versa.
The only obstacle is, that when you use Facebook as your Facebook page, many profiles, photos etc. my be blocked from being liked or shared by you. I'm not sure, but it seems, that you're limited to liking, sharing and commenting other Facebook Pages only. You can't do that on a regular Facebook profiles. You need to switch back to your original profile to do this.
So currently there is no need to use
Add to My Page's Favorites option. All you need to do, is to switch to use Facebook as your Facebook Page and like, share etc. just like normally.