Depends on the object (ie provider). In your string, Ifxoledbc.2
MS has a default one MSDASQL, the string would look like
Provider=MSDASQL;DSN=myodbc;uid=myid;pwd=mypwd
You'd use an odbc driver, with a DSN that can already connect. I've run into a problem in the past with with some transactions and transaction isolation levels leading to crashes.
I suggested a different direction to see if you can avoid them. Try the Informix provided Driver, or a 3rd party one. If the Informix one isn't the cure, try
http://www.openlinksw.com.
Disclaimer, I work in tech support there. We have demo drivers available, and we will help you get them running.
Jay