Asyncronous, non blocking back- connector for Openldap

Hello all,

I would like to know if any of you have ever experiment a NONBLOCKING, 
socket based back-* for OpenLdap server.

For obscure reasons, out of the scope of this mailing list, I must 
compile openldap slapd with non-threaded option activated.

The data storage, we get data from, is accessed via standard TCP socket; 
but some read can take time. Thus we cannot wait in a blocking TCP read .
We start our experiment with a modified version of back-sock ( using TCP 
), but this back- use a blocking scheduling model.
Thus,
    How can we put in slapd scheduling loop an alien socket managed by a 
back- library ? ( SLAPD_ADD.... ?)
    How can back- be scheduled on socket reception ( Listener* ?)
    How can we asynchrously send LDAP response, and set the context for them
    What should be answered at the first ldap request ( in the 
back_search() for example) to say 'will be answered later' ?

Any help, or pointer to help,  even for only one of this point, would be 
much appreciate!

hp tf