Ranjani Bettadahalli and Paul-John To have written an excellent new developerWorks article on how to set up ODBC connectivity to IDS on Mac OS X: Integrate Informix ODBC applications on Mac OS X with Informix Dynamic Server, Part 1: Installing and registering the ODBC bundle driver graphically Exploring Informix CSDK ODBC connectivity on Mac OS X using Apple's Graphical Data Source Utilities.
The Informix Client SDK for Mac OS X was originally 64-bit only, but a 32-bit version was recently released which expands the number of applications and drivers that can take advantage of ODBC connectivity to IDS.
The article takes you through every step of installation, including some of the finer points such as configuring the Launch Services facility (launchd) which applications use when they start up, to make sure they have access to the INFORMIXSQLHOSTS and ODBCINI environment variables.
Part 2 of this article is going to show how to use ODBC connectivity to IDS with FileMaker Pro and OpenOffice.org tools.
Informix applications on Mac OS X