Is it possible to install MS Office 2007 Standard English Language Pack on top of Japanese version of Office?

Question

I have a Japanese version of Microsoft Office 2007 Standard, upgraded from Microsoft Office 2003 Standard.

Is it possible to install an English Language Pack or English Language Interface Pack?

Answer 1

I've never done it, but it seems like it's possible.
Here's what says Microsoft's FAQ for Language Packs for the 2007 Microsoft Office :

An Office Language Pack enables a user or organization to add localized UI and document proofing tools for an additional language to their base 2007 Microsoft Office language deployment and to easily switch between them.

So it looks like you can add languages to any base/starting Office installation.

Office language packs are apparently less limited than Windows language packs. The later can only be added to an English version, but Office is not so limited.