If you don't mind playing with HEAD code, you could try this patch

ftp://ftp.openldap.org/incoming/pierangelo-masarati-2010-04-14-extra-attrs.1.patch

Never mind, I think I already made it incompatible with HEAD code. I'm going to commit this stuff anyway, please stay tuned.

p.

You need to add

extra_attrs OpenLDAPACI

within the database that contains the offending slapo-rwm instance.

Please test and report. Thanks, p.