Using binding and localisation

I try to create something like that:

<Label Text="{Binding oResult.hi, StringFormat='Hallo: {0}'}" />

And it works fine! But i wish that the String "Hallo" should get out from the resx file.

Like this:

<Entry Placeholder="{i18n:TranslateExtension Text=password}" IsPassword="true" />

Also i will do a combination of both.

Thank you!