First of all, the site Hacking WD MyBook World it the best place to start. Follow the manual for first steps, and be aware that in order to successfully complete the most important 1.st step (Enabling SSH with Method 1) - your router must have internet access (not only your computer from which you are accessing the router).

Again, finish the second step - install Optware Package Management (package manager, similar to Yum).

And, now, for Midnight Commander  type:

/opt/bin/ipkg install mc

ldconfig(must execute this)

/opt/bin/mc

And, it’s working!

And, at the end, disable Mionet. You could install nano with: /opt/bin/ipkg install nano, and alternative Web interface on port 8080 as explained here.

And, because I want to change Port on which ssh deamon is listening, I had to change nano /etc/services (not /etc/sshd_config), because sshd is started throe inetd.