You will need the server root access to install Fantastico :
cd /usr/local/cpanel/whostmgr/docroot/cgi
wget -N http://www.netenberg.com/files/free/fantastico_whm_admin.tgz
tar -xzpf fantastico_whm_admin.tgz
rm -rf fantastico_whm_admin.tgz
Do this on shell then go to whm and click on install with stable version.
