Technically, yes, this would be possible. The only problem is will have to have custom marshaller/unmarshaller on the server side. Currently the marshallers use java serialization to convert the bytes on the wire into java objects and then back into binary data to put on the wire. So would have to come up with your own standard for what your different clients (Java, Delphi, Flash, etc.) write to the network wire (i.e. what the byte stream will be). Then will have to write the unmarshaller so can read those bytes off the wire and create a jboss remoting InvocationRequest out of this data.
There are no examples for this, but would be willing to help with writing the custom marshaller/demarshaller if you'd be willing to have it included within the project when done.