PikalaxALT wrote on Aug 24^th, 2013 at 12:02am:

Can the keyboard-for-FMC mode toggle be mapped to a keystroke, like with the other 737NGX?

It is. To switch it ON/OFF:

To activate CDU keyboard control press Ctrl+Shift+K
To deactivate CDU keyboard control press `

This information is on Page 33 of the ‘777 Captain’ FLIGHT MANUAL Part II – Aircraft and Systems (csx777_manual2.pdf).

If you don't already have the manuals, you can get them here: http://www.captainsim.com/products/x777/manuals.html