Installation process is done with yum:
When completed - run a command to setup mod_lsapi and register LSPHP handlers in Plesk Panel:
The command adds LSPHPXY alt-php PHP handlers to Plesk Panel so they become available for domains.
Managing PHP handlers is fully done with Plesk Admin according to their documentation: http://download1.parallels.com/Plesk/PP12/12.0/Doc/en-US/online/plesk-administrator-guide/70669.htm
Enabling lsapi for single domain is done with Plesk Panel > Subscriptions > [subscription name] > Hosting Settings > PHP Support, select desired LSPHP handler for domain.
Enabling lsapi for multiple domains is done with Plesk Service Plans > [Plan name] > PHP Settings > PHP support, select desired LSPHP handler to be used by all users under a plan. If a subscription is not locked (user changed nothing in it), after clicking ‘Update and sync’ domains will start using lsapi.
There is no way to switch all plans to lsapi - it should be done one-by-one .