A quote from their blog: From Yahoo!'s point of view, any kind of signed-in user involving with Yahoo! solutions is a valued individual, whether she validates using a Yahoo!, Facebook, or Google ID.
How To Sign In Yahoo Using Facebook
Login to Yahoo Mail account on PC/Desktop computer
First you require a username as well as password; currently open internet browser from your computer/desktop. Then open web page www.yahoomail.com on it. To launch their brand-new "one-click" sign-in simply click the "Sign in with: Facebook" symbol on the Yahoo! login display. That's all you require; to get accessibility of your Yahoo mail account.
Login to Yahoo Mail account on Mac computer system
If you are a customer of Mac computer system then Safari must be your web browser. Safari is the most effective surfing option for Mac OS; Safari is quick, quicker and easy to use browser. You can quickly access your Yahoo Mail account with it. See, how you can login with Yahoo mail account on Safari web browser. Just open Safari and kind www.yahoomail.com; you will certainly be directed to Yahoo mail sign-in web page. To launch their brand-new "one-click" sign-in simply click on the "Sign in with: Facebook". You are then fully signed right into Yahoo!
Nonetheless, an advice- you still will not be able to sign into a mobile or desktop client using Google OpenID.
I wish this article can aid you. Thank you ...