Could you also trace the installation PIDs to see what it might be doing at the point it fails?
Code:
ps aux | grep latest
lsof -p PID#
Here you would replace PID# with the PID of the installation process. You might even need to use "pstree -u root -p" to track down the installation processes to see them in a tree listing for what is the last running latest process and then "lsof -p PID#" for that process.
Additionally, depending on how much of cPanel has installed, you might check /usr/local/cpanel/logs/error_log for any details or /var/log/cpanel-install-thread0.log and /var/log/cpanel-install-thread1.log files (these last two are the cPanel installation logs).