authenticated LDAP, multiple directories?

Has anyone configured exmh to use multiple LDAP directories?

Has anyone configured exmh to query an LDAP directory server that demands 
authentication? I'd really, really, really prefer something like the way GPG 
keys are handled--with a pop-up window for entering the password, and then a 
user-selectable preference for caching the password.

I could configure my LDAP client with a clear-text password stored in a file, 
but that's just fundamentaly horrible.

Thanks,

Mark