The only supported method to create OVD 11g adapters is to create it using ODSM console. However if you want to create the adapters without using GUI, you can do so by updating adapters.os_xml. This is the file where all adapter details gets stored.
Let me talk about my exploration right from the beginning. I have read a metalink note 1336191.1 and thought that adapters can be created through command line as well. This is the Oracle documentation link that it points.
I suspected looking at the documentation as it talks about libOVD adapter used in OIM LDAP sync process. Anyhow, I gave a try using wlst.sh