With ODBC it seems that anything can interconnect with a respective ODBC driver.
Having ASP/PHP connecting to an Informix Database seems very possible, but you'll need to install the the informix ODBC driver.
You can get the Informix ODBC drivers through the SDK on the following site:
http://www-306.ibm.com/software/data...ix/tools/csdk/
- A.Kahtava