well...you probably can't override those values with ini_set() AFAIK...
my first idea would be:
spit out a cookie to the client with a unique id, write a container and pass references to variables you want in sessions to that container...
next write a function to serialize that container and save it to a database comlpete with a timestamp and the unique id, and register that function with register_shutdown_function()
and of course a function to unserialize that container...
in short terms: write your own session management...
sorry...maybe someone has a better idea...
regards
addon: you can change
session.gc_maxlifetime
with ini_set()...
http://php.net/ini_set
sorry =)