The easiest way to do this would be to serialize the Object from the existing project into XML and then just put the XML into the SoapUI project. Otherwise it will require a lot of manipulation on a DOM level of the XML or deserializing the XML from the SoapUI request and then aligning from Object A to Object B. Essentially, a huge pain.
Not to mention by serializing the object into XML it will make it far easier to export, save manual backups or even have something to display to the user to say 'Hey, is that what you really want to do?' if you so desire.