Is it possible to use XDoclet without Ant?
It's not possible to use XDoclet without Ant, for some good reasons. But anyway you should be able to invoke Ant from make for example.
Obviously it's ridiculous to add @tags to source code for one-time operations where you generate something from the @tags and never come back to use the @tag again. So @tags are good for cases where you run something continuously, for cases where the code changes and the generated stuff should be regenerated based on the new code/@tags. Ant is a great tool for automating this procedure, it's a great tool for "Continuous Integration".