So, you finally came here finding an alternative solution for your Plesk server for wordpress and other CMS for uploading files via web server. I will help you solving the issues, the alternatives for suphp are mpm-itk and mod_ruid2, I tried configuring mpm-itk in the plesk server but it was not supported properly, there were few sites which were diplaying blank page, so I prefer mod_ruid2 over mpm-itk for plesk environment.
First download the atomicorp repository if you dont have the latest one using the below commands. This may over write the current atomic repostory
cd /root wget http://www.atomicorp.com/installers/atomic chmod +x ./atomic ./atomic
Then download the apache module mod_ruid2 via yum
yum install mod_ruid2
then edit the config file at /etc/httpd/conf.d/ruid2.conf and add the below similar configuration into it.
<Directory /var/www/vhosts/domain.com> RMode stat RUidGid ftpuser psacln RGroups psaserv </Directory>
save the file and restart apache service.
That’s it you are done, make a note that you need to manually add all the domain name where you need to run the website on it’s own username. Not sure if there is any other alternative to automate it.