Backport175 comes with an Eclipse Plugin. It has been tested on Eclipse 3.0 but should work with Eclipse 3.1.
Use the Eclipse plugin manager to get the plugin from the following update site: http://backport175.codehaus.org/downloads/eclipse
Once installed the plugin allow to add the backport175 nature to your project. Select your project, right click on it and turn on the nature.
When you will build, the annotation will be compiled into the compiled class file just a the Java 5 compiler would do with Java 5 annoations.
Errors (like bad annotation syntax) are reported as compilation errors and will appear in the "Problem" view.
You will have to fix them or Eclipse cannot build succesfully your project.
Errors location are marked with an error marker.
Successfully compiled are marked with an @ icon (may differ from this picture)
Ignored annotation (f.e. regular JavaDoc) are not marked at all.
Simply remove the backport175 nature from your project.
If you are using an annotation.properties file, you need to register it in your module build settings. Right-click on your module, select Properties, and configure the Backport175 annotation.properties entry here.