If it's the same as my Mavic Ksyrium SLs, it's blindingly simple. Pop off the end-cap and shield on the non-drive side. Pick it up from the floor and clean it. Put a mahoosive hex key down the hole and a smaller one down the drive side axle and unscrew. The axle will separate into two and you will drop at least one bit on the floor. Carefully lift off the freehub while turning it backwards. Take great care not to lose the washer that's lying between the freehub and the small hub bearing you see. Carefully remove the two pawls and springs and clean them. Clean up the plain boss on which the freehub rotates, removing the black rubber seal and cleaning that up. Push the seal back on, replace the pawls and springs, oil everything with 3 in 1 oil and slip the freehub back on while turning it backwards, then remember the small washer, take the freehub off and replace it. Tighten the axle, replace the end cap and feel happy.
You will be surprised at the simplicity of the system and worried at the black colour of the old oil. Don't be tempted to use a heavier oil, all that happens will be that the freehub will drag while freewheeling and your chain will sag. Once that plain boss gets worn the freehub will begin to oscillate madly on it making a howling noise, commonly known as the "Mavic howl of death." That's why you need to disassemble it and lubricate it every 6 months.
