The official site of u7z is : http://sgh-punk.narod.ru/files/u7z/

INSTALL
=======
- edit /usr/share/mc/extfs/extfs.ini to add "u7z" after urar.

- edit /usr/share/mc/mc.ext to add :
=-=-=-=-=-= Cut -=-=-=-=-=-
regex/\.(7z|7Z)$
	View=%view{ascii} 7za l %f
	Open=%cd %p#u7z
=-=-=-=-=-= Cut -=-=-=-=-=-

This must be added before Manual pages Lines to prevent handle 7z archive
like man page

- copy u7z to /usr/share/mc/extfs

- launch mc to try ;)