How can I use same JAXB class to marshall and unmarshall into different namespaces?

Note: this is with Java 7. Also, I am not using JAXB to generate anything from a schema. I only/merely want to use JAXB to deserialize pieces of existing SOAP messages. So the JAXB beans are "hand-written".

I am trying to deserialize the following XML with JAXB. I do not have access to it as a string. Rather, I am getting it as an org.w3c.dom.Element object:

<SynchInfo xmlns="urn:InitronSOAPService">
    <HandshakeInfo>
        <dnsName>foo.bar</dnsName>
        <ip>1.2.3.4</ip>
        <id>TheId</id>
        <key>SomeKey</key>
        <version>1.0</version>
    </HandshakeInfo>
</SynchInfo>

And then I would like to marshall that back into a different Node that is part of a message belonging to a different namespace.

I first tried to write a HandshakeInfo class that didn't mention namespaces at all:

@XmlRootElement(name = "HandshakeInfo")
@XmlAccessorType(XmlAccessType.NONE)
final private static class HandshakeInfo
{
    private String version;
    private String id;
    private String key;
    private String ip;
    private String dnsName;

    public String getVersion() {
        return version;
    }

    @XmlElement(name = "version")
    public void setVersion(String version) {
        this.version = version;
    }

    public String getId() {
        return id;
    }

    @XmlElement(name = "id")
    public void setId(String id) {
        this.id = id;
    }

    public String getKey() {
        return key;
    }

    @XmlElement(name = "key")
    public void setKey(String key) {
        this.key = key;
    }

    public String getIp() {
        return ip;
    }

    @XmlElement(name = "ip")
    public void setIp(String ip) {
        this.ip = ip;
    }

    public String getDnsName() {
        return dnsName;
    }

    @XmlElement(name = "dnsName")
    public void setDnsName(String dnsName) {
        this.dnsName = dnsName;
    }
}

But when I used that to try to deserialize the Element object containing the HandshakeInfo element, I got the following exception:

javax.xml.bind.UnmarshalException: unexpected element (uri:"urn:InitronSOAPService", local:"HandshakeInfo"). Expected elements are <{}HandshakeInfo>
    at com.sun.xml.internal.bind.v2.runtime.unmarshaller.UnmarshallingContext.handleEvent(UnmarshallingContext.java:647)
...

So then I tried adding , namespace="urn:InitronSOAPService" to all the element and attribute (in this case none) annotations in the class. (Or, alternatively, used an @XmlSchema annotation in a package-info.java file.) That worked for deserializing that element in that namespace.

But when I tried to use the class to serialize into a different namespace I (not entirely unexpectedly) get stuff like this:

<SomeMessage xmlns="urn:differentNamespace">
    <ns5:HandshakeInfo xmlns:ns5="urn:InitronSOAPService">
        <ns5:dnsName>foo.bar</ns5:dnsName>
        <ns5:ip>1.2.3.4</ns5:ip>
        <ns5:id>TheId</ns5:id>
        <ns5:key>SomeKey</ns5:key>
        <ns5:version>1.0</ns5:version>
    </ns5:HandshakeInfo>
</SomeMessage>

That's not what I want. I want the serialized thing to be part of the urn:differentNamespace.

So is there any way to use the same JAXB class in multiple namespaces? Or am I stuck with having to multiple copies of classes with each one annotated to be in the appropriate namespace?

I have seen some tricks using filters, etc. but those tricks seem to be assuming the XML is being read from or written to a stream or a file. Again, for both unmarshalling and marshalling I am working with org.w3c.dom.Element objects.