The sound you'll hear sounds like the character selection sound effect. Once this is activated, simply go all the way to the left and it'll go off the screen. There it will list Kazuya with no portrait. When you select him it will ask you to either place in Tekken 2 or to cancel and select another character. If you do have Tekken 2, it will take about 4 seconds and load up his character data and ask you to place back in the Tekken 3 CD.
From then on you can keep using him but if you select another character, you will have to swap discs again. It looks like the theater mode wasn't the only way Namco has incorporated the disc changing feature. Hopefully other characters will make a special appearance such as Devil Kazuya or Jun.
We're [http://www.gaming-age.com] offering a free US game for the PlayStation to the person who can give us exact details on how its done.
Okay, here something stupid that I made up with Tekken 2's Practice Mode.
WARNING:this is very dumb, so if you don't like stupid stuff then don't read any further.
Okay, first go to Practice Mode from the main menu. Select any character. Then press start to bring up the Practice Mode options. Go down to Key Display and change it to "Player." Press start. Then enter this string:
(or in 1,2,3,4 notation)
Recognize the tune?? I apologize deeply. :-)