With the 4.0.x and 4.1.x SQL Developer releases, you can use Tools > Preferences > Database > Advanced > Configure Oracle Client to point to an Oracle full or instant client having a JDBC driver version which supports 9i.
With 3.2.2 it is a bit less convenient since you are reduced to copying the necessary ojdbc6.jar version to the sqldeveloper\bin directory. If your environment variables point to some inappropriate Oracle client, then you can force SQL Developer to use the copy in it's bin directory by starting it up with a custom script that sets ORACLE_HOME to sqldeveloper\bin.
For past discussions on this topic, see...
If possible, you should upgrade to the the latest SQL Developer, 4.1.3, and configure it to use an 188.8.131.52 instant client.