How can I change the language of a OneNote section (or page/notebook)

After some testing I can confirm that OneNote always uses the input language set in the Region and Language control panel.

However, you can combine any input language with any keyboard layout (at least in Windows 7), so the (hopefully temporary) fix is to add a new input language combined with the original keyboard layout.

This has a microsft-onenote-2010 tag, I can't tell how it works in 2010 but in OneNote2013 I did:

1. Select the text or page
2. Set the desired language in Review > Language > Set Proofing Language

and it worked.