I bought a suit for ZombieCon 2 years ago at Goodwill for $5. I highly recommend doing the same for this portion.



You don't need a suit, but it's nice for authenticity.



Open up the lid on the Dreamcast, to gain access to the bolt.

Remove the Dreamcast from the Harness.



Grab a white dress shirt (Again, Goodwill), and put it on.

Put the Harness on, and mark the locations where cutting will be needed in the front, so that the keyboad supports will fit through.



Cut a large slit down the back center of the shirt. This will allow you to get your arms in the sleeves when you put this thing on.



Three holes total: One for each keyboard support, and one large one in the back to fit the Dreamcast through.



Take off the Harness, and put on the suit jacket.



Put the Harness back on, and mark the back. Chalk will work well for marking, as it's easy to remove.



Take the Harness off again, and cut a small hole in the location you marked for the bolt in the bottom of the Dreamcast to fit through.



Put the shirt on the Harness, and the the suit jacket over top (As you would wear it)



Insert the bolt into the back of the Harness, and through the holes you made in the shirt, and then the jacket.



Put the Dreamcast on, and tighten the bolt.