Actually, before the SU34 looked like a SU34, Sukhoi created a prototype that had a side by side seating bulby cockpit, but it retained the nose of the flanker series. This aircrafts looked wierd, but it was designed to be carrier capable. It is this side by side seating aircraft that lead to the SU34. Considering the difference between that aircraft n the SU34 is the reshaped canopy n a longer tail sting, this is why they said the Su34 is carrier capable.
If they want to create a carrier capable SU34, it wont take much effort other than shortening the tail sting.
http://www.ausairpower.net/000-Su-27KUB-4ES.jpg
http://www.ausairpower.net/000-Su-27KUB-5ES.jpg