Ok, I have found a solution.
My bindings.xml
<jxb:bindings version="1.0" xmlns:jxb="http://java.sun.com/xml/ns/jaxb"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
xmlns:xjc="http://java.sun.com/xml/ns/jaxb/xjc">
<jxb:bindings schemaLocation="./myXsd.xsd" node="/xs:schema">
<jxb:globalBindings>
<xjc:serializable uid="1" />
</jxb:globalBindings>
</jxb:bindings>
And my ant options:
<xjc schema="./myXsd.xsd" target="../src/java" package="myxsd.xml" extension="true" binding="./binding.xml"/>