Ray,
Take a look at OPENLINK's ODBC driver. It allows Read-Only to an
Informix 7.X online database. Otherwise, check into the more
expensive Cognos Impromptu, which will allow you, as the DBA, to
set up a global catalog for all user, of which will connect to
your database, in which will prohibit updates, alters, joins,
tables etc.. All contingent on your requirements.