You can use the -n option to preview but not perform updates to the jti file.
Example:
java -cp [jt_dir/lib/] javatest.jar com.sun.javatest.EditJTI -n -o mynew.jti -l myeditlog.html "|/java/jdk/1.3/|/java/jck/1.4/|" myoriginal.jti
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