Homepage SEO setting problem in multilanguage site

Hi, every one.
I had setup a multilanguage website, but I could not find how to set the SEO options (title/key words/discription etc.)of the homepage for different languages. If I set in "General settings =>SEO", it works the same at any languages.
I saw www.nopcommerce.com home page for different languages is working well. Do I have to install any plugins?

My nop version is 4.0

Here is a work item for this feature.  We are going to implement it in the next version.