KSM and his 4 companions have filed a six-page response in the Gitmo MCA proceeding (stayed by the Obama administration). From the UK Guardian:

Five Guantánamo detainees claim responsibility for September 11 attacks
• Men call accusations 'a badge of honour'
• Pentagon confirms New York Times report
Daniel Nasaw in Washington
guardian.co.uk, Tuesday 10 March 2009 14.30 GMT

Five accused planners of the September 11 2001 terrorist attacks on the United States have said they are proud of the effort that killed nearly 3,000 people and called it a model of Islamic action.

In a filing with the Guantánamo Bay military commission trying them, the alleged co-conspirators describe themselves as "terrorists to the bone".

"To us, they are not accusations," the document reads. "To us they are a badge of honour, which we carry with honour. Many thanks to God, for his kind gesture, and choosing us to perform the act of Jihad for his cause and to defend Islam and Muslims".

The document, titled The Islamic Response to the Government's Nine Accusations, bears the names Khalid Sheikh Mohammed, Walid Bin Attash, Ramzi Binalshibh, Ali Abdul Aziz Ali and Mustafa Ahmed Al-Hawsawi, all of whom are currently held in a high-security camp at Guantánamo Bay. ....
The MCA order (simply entering and publishing the document) and the six-page response is here.