GmxLee has modified his FireFox OneNote Extension to install in Flock.

I’ve tested it with 4.10 and an hourly build of 4.11 with no issues.

Link: FireFox OneNote Extension (on AdminID.com with permission)

Note: Go to the extension Options and set your onenote.exe path after install.

Author: GmxLee

Official Site and more info: http://www.freewebs.com/onenote/