what end result do you want?
why do you think you need to extract the cia?
it might not help you depending on your situation.
i don't know if the cia is encrypted. if it is, do you have a 3ds that can run tools that are needed to decrypt the content?
if you do, you don't necessarily need the cia, you can download the files straight from nintendo and decrypt them on your 3ds, if you have the titlekey.
your best situation is if the cia is decrypted and then you won't have to decrypt the contents on the 3ds.
what do you want to get out of this?