Hi aravind,
I does not have more general tutorial of ROM instance. For ASIC design, different Memory Compiler have different usage. But commonly, you will be asked to provide ROM file (txt file) to the memory compiler and it will give out simulation model, liberty, lef and GDSII files.
For FPGA, usage of Coregen, Xilinx. You can view the help. It is simple.
And you want to import data from ROM to RAM?
what does your mean? Can you describe it clearly?
I am sorry for my understanding.