This is sucked from IBM document Q00764, don't hold me responsible if this doesn't work. If there is an issue, check permissions to the temp folder.

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
</configuration>

You can modify the app.config (or web.config in a web application) file to turn on the UO.NET client trace log. Here is the sample setting to set the trace level to 4. The log file name is c:\temp\myListener.log.

<?xml version="1.0" encoding="utf-8" ?>
<configuration>
  <system.diagnostics>
    <sources>
      <!-- This section defines the logging configuration for My.Application.Log -->
      <source name="DefaultSource" switchName="DefaultSwitch">
        <listeners>
          <add name="myListener"/>
        </listeners>
      </source>
    </sources>
    <switches>
      <!-- add name="DefaultSwitch" value="Information" /-->

      <!-- Set value property of Arithmetic switch to one of the following: 1(error), 2(warning), 3(info), 4(verbose) -->
      <add name="UniTraceSwitch" value="4" />
    </switches>

    <sharedListeners>
       <add name="myListener"  type="System.Diagnostics.TextWriterTraceListener" 
                initializeData="c:\temp\myListener.log" />
    </sharedListeners>

    <trace autoflush="true" indentsize="4">
      <listeners>
        <add name="myListener" />
      </listeners>
    </trace>
  </system.diagnostics>
</configuration>

When your project is compiled, the app.config file is copied to the project output folder and is renamed <program>.exe.config.

In a web application, simply run the application and the file will be created.

Requirements:

Install UniDK (uodotnet.dll)
Microsoft Visual Studio 2005.NET (Microsoft.NET Framework v2.0.50727 version)
Microsoft Visual VB.NET