For Samba I don't go through the hassle of converting existing info in the smbpasswd file - instead the accounts will be added with smbpasswd utility after changing Samba's config file.
Before we can add Samba accounts to the LDAP Server we need a schemafile wich is available from the samba-doc package:
#> apt-get install samba-doc #> zcat /usr/share/doc/samba-doc/examples/LDAP/samba.schema.gz \ > /etc/ldap/schema/samba.schema
Edit /etc/ldap/slapd.conf to include this schema and restart the server.
Now we can reconfigure Samba - you should stop Samba before doing so. Now edit /etc/samba/smb.conf and add some LDAP options to the global section:
passdb backend = ldapsam ldap server = 127.0.0.1 ldap admin dn = cn=admin,dc=my,dc=home ldap suffix = dc=my,dc=home
Restart Samba and give it the LDAP admin password with smbpasswd -w <secret>. Now you can add samba password to your existing users with smbpasswd -a <user>..