Hi Rhea, I think that rumour in Empire was based on something Lucas said about Park coming back. However, snce the day he said it there has been no further indication that it would actually happen.
I contacted Ray Parks management some time ago and they told me there were no deals for Ray to be in Episode II or III.
OK, I'm dooming myself to having to go find this now but as I saw it reported the dtory went like this.
Lucas was collecting some award or something and made a comment about having enjoyed working with Ray Park and looking forward to working with him again on Episode-II.
Everybody thought it was strange at the time.
i thought mark hamill was doingthe voice for one of the CGI aliens in episode 2. As for 'special guests' is it not possible george said what he did about ray park knowing the rumours that where going on at that time about maul's return to throw us lot off the scent? I suppose he cold return as a hologram or something ? Or maybe a flashback in a dream anakin has of him killing his old friend qui gonn , something that could build up the anger inside of him.