Add RPMForge repository

wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm
rpm -ivh rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm

Install 7z

yum install p7zip

Extract file

7za x [7zfilename]

Compress file

7za a -mx=9 7zfilename.7z [filename/directory]