Well I think what you need is a way to gain root and a text editor.
So if the "/var/lib/mce/mode" needs root access to edit it you need something like rootsh.
The actual magic happens with a text editor like nano or vi or vim.
So install one of them, I like and use nano.
Then to edit you type, if root access is needed, in xterm.
sudo gainroot
Then to edit "/var/lib/mce/mode"
nano /var/lib/mce/mode
Then you type "normal" on the lines of text and save the file. Before you use sudo gainroot see if you can edit and save the file without it first. If you accidentally change the permissions of the file you can have a big headache.