Hi Prodip

Once you modeled the disordered carbons, you need to check the distance between the c-c atoms, if required dfix them and then add H as usual. Shelxl will atomatically locate H accordingly with the similar occupancy for Carbons.

I hope it helps 

The program CRYSTALS (see link) can readily be used to add hydrogens in calculated positions according to your assignments of bond length and carbon hybridization. The program contains many useful facilities to allow you to build and optimize all aspects of your model.

http://www.xtl.ox.ac.uk/crystals.1.html