This article spreads light on installing Plesk packages into a VPS using EZ templates ! This applies to plesk virtuozzo.
1) Make sure the user is using EZ templates, the OSTEMPLATE variables in the veid.conf should be something along the lines of OSTEMPLATE=.centos-4-x86³. Please note not all OS templates support Plesk. For example CentOS 4 x86 does support it, but CentOS 4 x86_64 does not.
2) Install the actual templates and required packages:
vzpkg install VEID devel jre jsdk mailman mod_perl mod_ssl mysql php plesk8 plesk8-api plesk8-backup plesk8-mailman plesk8-modules plesk8-spamassassin plesk8-tomcat plesk8-vault
If you receive an error about a specific template already being installed just remove it from the list and keep trying.
Once this succeeds the license key must be run inside the VPS and then Plesk restarted.