In Office 2010 you can customize Office apps to use your preferred services!, available in Word, Excel, PowerPoint, Outlook, OneNote, Visio and Publisher. Follow steps below to change / add translation service:
Change translation service:
1. Click on Review tab, then click Research, and on Research pane – where indicated, select Translation – Click hyperlink: Translation Options… a dialog box opens up: If you only want to use Bilingual dictionary and do not want to avail the services of machine translation, you can uncheck “Use online machine translation” checkbox. Just click on the arrow for the translation services of the desired language pair and choose your preferred provider.
Add New Service:
1. If it’s not already showing in the Research Pane. Click on the “Research options…” hyperlink at the bottom of the pane, this opens a dialog box.
2. Click on “Add Services…” in Research Options dialog.
3. Enter URL of the service provider. Don’t forget to press the “Add” button after you’ve entered the URL. You may now get a couple of other dialogs confirming the addition of the new service.
Source:→ Office blog