So you have found some annoying data synchronisation system that requires a DSML SOAP Gateway to you OpenLDAP directory server and having googled on the subject found that there is not very much out there that will help you. Hopefully this will help you solve that problem as long as you don't have a huge phobia of Java.
Firstly you will need to download and install tomcat, which is simple on FreeBSD:
portinstall -P www/apache-tomcat6
Then you need to enable and start the tomcat server:
cd /usr/local/apache-tomcat-6.0 mkdir work chown -R www:www work temp logs webapps echo 'tomcat60_enable="YES"' >> /etc/rc.conf /usr/local/etc/rc.d/tomcat start
Once that is done you will need to grab the latest DSML SOAP gateway from here: http://www.opends.org/promoted-builds/latest/
Once you have the war interface you can unzip it and configure it to point at your server.
mkdir dsmlgw cd dsmlgw unzip ../OpenDS-2.0.0-DSML.war
Now you need to edit dsmlgw/WEB-INF/web.xml to point it at your directory server.
Once you have done this you can deploy the application in the tomcat server by moving dsmlgw into /usr/local/apach-tomcat-6.0/webapps.
And that is all you need to do if you have an ldap server that is configured to allow anonymous access.
You can now point you DSML client at http://server:8081/dsmlgw/DSMLServlet and have some fun.
If you need to authenticate to the ldap server you need to have the client use http basic auth with either the tomcat server or an apache reverse proxy, the username should be the bind dn and the password should be the bind password. If you have a reverse proxy configured to use basic auth but the usernames and passwords are not valid in the ldap server and the ldap server allows anonymous connections then you can use mod_headers in the apache server to remove the authorization header before passing the data back to the tomcat server.
If you have an application (such as postini) that asks what sort of DSML gateway and ldap server are being used then I had the best luck with setting the client to interop with 'Lotus Domino'.