Session handler emulation
Scache includes also session handler emulation with enables clients already using php's own session management to take benefit of scaches network accessible storage.
Unfortunately scache's session handler emulation is very poorly tested mostly due to scached original mission to provide more flexible replacement for session handler.
In simples form you need configure php to use scache as session save handler by assigning it in php.ini and optionally specifying hostname and port scache module's session handler to connect if scaches is not running locally.
; in php.ini session.save_handler="scache" ; optionally set connection information ; scache.default_host="remote.host.org"
These parameters can also be changed with ini_set() function, but that implies modification to existing code and thus is often undesirable. Settings can also be set on apache's directory of virtual host basis with apaches php_admin_value directive.
If scaches session handler happens to work, you can probably without modifications to code share same session between several frontend servers and implement simple round-robin redundant frontend service.