Get jconnect60.jar (Sybase IQ Driver)
Put Driver into /iReport-4.0.1/ireport/modules/ext/
In iReport go to Tools/Options
Go to iReport option
Go to Classpath tab
Click add JAR
Browse to find Driver in /iReport-4.0.1/ireport/modules/ext/
and select jconnect60.jar
Select ok.
Driver added.
Now when you add data source
Use com.sybase.jdbc3.jdbc.SybDataSource as your jdbs Driver
and jdbc:sybase:Tds:localhost:2638/MYDATABASE as your URL