Using a external OpenLDAP server

Hi everyone.
In our business we have a separate ldap server and Windows AD.
I am aiming to take away windows AD and use UCS, but I don’t know how to use a External LDAP with UCS.
I Saw in Q&A that you can use and external OpenLDAP server and for that you need to use the listener feature in UCS.
And then, for that I start to reading the documentation about listener
and even putted the in
that worked after a few fixes (its in python 2 I think)
But I am lost now how a listening can change a main parameter like the configuration for main ldap master server?
I saw a file but looks like he is more a guy that adds another ldap server (I am not sure of that)
Can someone give me some directions or ideas for that?

Thanks in advance, with all my heart, Ricardo.