Found the solution, it seems there's a "persistent_list" hash object, so I'm able to do:
zend_hash_find(&EG(persistent_list), ...
To find persistent data ( allocd with pemalloc obviously ), and
zend_hash_update(&EG(persistent_list), ...
To save new instances.
( Found this in the PostgreSQL php extension source code. )
http://devzone.zend.com/446/extension-writing-part-iii-resources/#Heading8
Anyone interested in my approach, it's here https://github.com/evilsocket/phpgibson