The AN-2 does not have an EASA type certificate and so the crewing and licensing requirements are a matter for the state of registry of the particular aircraft concerned. The requirements may not be the same in all states of registry - some may accept a JAA licence without validation, others may not.
So far as claiming hours for JAA licensing purposes is concerned - if the aircraft is classified as single-pilot, you obviously cannot claim P2 time at all and if the aircraft is classified as multi-pilot you cannot claim P2 time unless you hold a valid multi-pilot type rating issued or validated by the state of registry.
If you do intend to claim the hours for JAA licensing purposes, you can log them any way you like.
Last edited by BillieBob; 19th Jun 2010 at 17:10.