Looking at the source code for LdapIdentityStore there is only 1 logging statement in the code (a warning if the search scope is set incorrectly) so there is no way with Seam logging statements alone. Seam just uses JNDI to speak to the LDAP server so you may be able to turn logging on for the particular implementation you use.
You have another 2 options
- attach a debugger using your IDE and step through the code - you should be able to see all the variables in scope at any point in the code
- look at the request 'on the wire' using a network protocol analyzer such as Wireshark - http://www.wireshark.org.