Storing with FilterName still doesn't work for me. I get:
"Error saving the document Untitled1. Wrong parameter. The operation was 
started under an invalid parameter". Next I get an IOException.

My FilterName "swriter: HTML (StarOffice Writer)" should be valid. (?)

A code snippet: 

    Object oDesktop = xMultiServiceFactory.createInstance
("com.sun.star.frame.Desktop");
    XDesktop xDesktop = (XDesktop)UnoRuntime.queryInterface(XDesktop.class, 
oDesktop);
    oUnoObject = xDesktop.getCurrentComponent(); //Writer

    XStorable xStorable = (XStorable)UnoRuntime.queryInterface(XStorable.class, 
oUnoObject);
    PropertyValue[] fileProperties = new PropertyValue[1];
    fileProperties[0] = new PropertyValue();

    fileProperties[0].Name = "FilterName";
    fileProperties[0].Value = "swriter: HTML (StarOffice Writer)";
    try {
      xStorable.storeAsURL("file:///g|/openoffice60-
2/user/work/teststore.html", fileProperties);
    }

Callstack:

com.sun.star.io.IOException: 
	at com.sun.star.lib.uno.environments.java.Proxy.invoke(Proxy.java:146)
	at com.sun.star.lib.sandbox.generic.DispatcherAdapterBase.invokeSec
(DispatcherAdapterBase.java:91)
	at com.sun.star.lib.sandbox.generic.DispatcherAdapterBase.invokeV
(DispatcherAdapterBase.java:145)
	at 
JSGencom_sun_star_frame_XStorablecom_sun_star_lib_uno_environments_java_Proxy.st
oreAsURL(Unknown Source)
	at java.lang.reflect.Method.invoke(Native Method)
	at 
com.sun.star.lib.uno.environments.java.java_environment$HolderProxy.invoke
(java_environment.java:161)
	at com.sun.star.lib.sandbox.generic.DispatcherAdapterBase.invokeSec
(DispatcherAdapterBase.java:91)
	at com.sun.star.lib.sandbox.generic.DispatcherAdapterBase.invokeV
(DispatcherAdapterBase.java:145)
	at 
JSGencom_sun_star_frame_XStorablecom_sun_star_lib_uno_environments_java_java_env
ironment_HolderProxy.storeAsURL(Unknown Source)