There are a few ways of doing this. You can use netgroups like NIS or you can just specify ldap filters. We use ldap filters. When setting up the ldap auth string we use a specific search descriptor like this:
serviceSearchDescriptor=shadow:ou=people,dc=some,dc=domain?'attribute=SomeH ost'
You can use & and | in your query, just watch out for how it reformats the query. It seems to automagically add the surrounding (). We've built the filter as such:
'&(attribute=SomeHost)(attribute=SomethingElse)'