There is another way to get what you want. You can turn off the built-in logging and add a JSS process trigger that does custom audit logging.
For example, to audit logins and logouts in the format you need, go to the Events panel, select the Process Triggers tab, click Add, enter something like 'Auditing' as the name, and then choose the 'Log in' and 'Log out' Events. Now select 'JSS script' and enter the following two lines:
var log = EnterpriseDT.Util.Debug.Logger.GetLogger("Audit");
log.Audit(event.type + "|" + event.loginUserName);
and click Apply Changes. It should start logging straight away, but you'll see tabs before and after the message your code logged. To replace those with '|', you'll need to set the ConversionPattern in your LogConfig.xml file to use '|' instead of tabs, i.e.
<param name="ConversionPattern" value="%date{dd MMM yyyy HH:mm:ss}|%message|%newline"/>
I think you'll need to restart the service before the new ConversionPattern is picked up. Also, the built-in audit logger resets the ConversionPattern, so if you accidentally enable it you'll need to restart the service so that your ConversionPattern is picked up again.
The Javascript code I included above is only really useful for logins and logouts, so you'll need to add code to include file-names if you want to log file operations, such as downloads and uploads.
Does that help you?