Can a Wallet be used with SQL Developer? How?
One way to do this is to specify an Advanced Connection Type and enter a custom JDBC URL as follows:

jdbc:oracle:oci:/@myDatabase

In addition the "OS Authentication" check box needs to be checked. This would seem to cause it to pass the OS username and password, but apparently (perhaps because I don't have NTS set as an authentication service in my sqlnet.ora) it does not and instead uses the wallet.