RT3 external user lookups on inbound mail

I’m a long-time user of RT2 and of this list but have been off of it for a
few months. I’ve just started upgrade from RT2 to RT3 (3.0.2pre4) and am
configuring RT3. Under RT2, I’ve configured LookupSenderInExternalDatabase
and defined the LookupExternalUserInfo method in the config.pm file, but I
don’t see where this configuration data should rest within RT3. I do see
SenderMustExistInExternalDatabase and see that its documentation within
the RT_Config.pm references LookupSenderInExternalDatabase, but I’m just
missing the link. Any help/pointers would be good.

On a second note, what is the general migration path for custom Actions,
Conditions, and Scrips from RT2 to RT3?

Thanks,
Christian

Christian Gilmore
Technology Leader
GeT Support Application Development
IBM Software Group