Xbox 360 controller and a mouse/keyboard with a PPIII (PS3?) copy of the game, seems legit ;)
IIRC you could plug a mouse and keyboard into the PS3, I remember a guy on dutch TV saying that he felt bad about abusing that in Unreal Tournament 3.(but not bad enough to stop doing it)
The xbox controller is a bit harder to explain. Although the PS3 was a pretty open platform, maybe Shirakaba is a bigger nerd than we expected?