There are many ways to play osu!mania. Aside from the usual Rock Fever & O2JAM layouts, there is the DanceDanceRevolution layout I produced and to help contribute to in the osu! community.
In order to get the full experience of the DanceDanceRevolution layout for osu!mania, you will need a MAYFLASH Gamecube Controller Adapter and a dance mat that can work on the Nintendo Gamecube and Wii. Also, you may need to re-map the buttons and panels via in-game button configuration or JoyToKey*.
* In my opinion, I prefer to use JoyToKey because I can map all the key combinations needed to activate music and mod selection, along with the ability to skip most tracks' intros, and to pause the game using a dance mat. You will have to do all of the JoyToKey configuring in order to get it working.