getting the oid for a new tuple in a BEFORE trigger

Hi,

we need to control database changes within BEFORE triggers.
There is no problem with triggers called by update, but there is
a problem with triggers called by insert.

We strongly need to know the oid of a newly inserted tuple. In this case, we 
use tg_newtuple of the TriggerData structure passed to thetrigger function, 
and its t_data -> t_oid will have the value '0'.

Using BEFORE and AFTER triggers would make our lives much harder.

Is there any way (even hack) to get the oid the newly inserted tuple will 
receive?

Thank you very much,

Markus