I have disassembled several Dura-Ace 740X freehubs. These are among the few Shimano freehubs that are worth the effort, as most freehubs are inexpensive and common.
First, leave remove all of the hub guts including the axle, bearings etc. Leave the freehub attached to the hub. Use a metal punch to remove the outer bearing cup - by rotating clockwise. Yes, it is reverse threaded.
The cup and 2 slots are made of very hard metal, I've never come close to doing damage. A good precaution is to marinate the cup threads with penetrating oil in advance.
When the hub shell is loose, be prepared for a cascade of tiny ball bearings. Do not lose or damage the paper-thin shims that sit under the outer cup.