RESOLUTION
This can be done by adding:
upload_tmp_dir /tmpOr if you wish to specify upload_tmp_dir for one domain only add the following line in the domain's vhost.conf file.
into php.ini.
<Directory /path/to/vhosts/domain.com/httpdocs>
php_admin_value upload_tmp_dir /tmp
</Directory>
Once the changes have been made to the file the 'websrvmng -a -v ' utility must be run in order for the changes to take affect.