Answer
Yes, at least for the Enterprise Explorer interface: configure the ADFS authentication model per the standard technical documentation the same way you would for full ADFS-only authentication, then, at the individual USER level, set each specific user's Directory ID to either their AD-style identity, such as USER@DOMAIN.COM, for ADFS-authenticated users, or leave it as their plain database account name for DB-authenticated users. AD-authenticated users then log in using the normal IFS Enterprise Explorer link, while DB-authenticated accounts, like shared workcenter-style accounts, instead need to use the separate IFS Enterprise Explorer 'Admin' login link, the same one used to log in directly as IFSAPP, to bypass the ADFS-only normal login path.