Do I need to be a hacker?

[Yagxter]

What kind of knowledge do I need to have to extract Japanese scripts? I want details.

[Fiddle]

For some VN engines, tools have already been made to extract and replace the scripts and images, and anyone with a little patience can figure them out. You may want to consult this thread, although it's fairly dated.

Other VN engines may require hacking, but I recommend you scour the internet to see if anybody else has done it first. If somebody has worked on a VN translation (even a dead one), you may be able to contact them for the relevant tools, assuming they haven't been made public already.