Step 2: download a hex editor and a file extractor (likely quickBMS)
Step 3: learn how to use quickBMS and write a script to extract all necessary files from proprietary archival formats used for your games files
Step 4: hex editor! Open files one by one and look for stuff that might be text or compressed text files
Step 5: if you determine they are compressed write another script to extract those...
Step 6: once you have found, extracted, found a way to edit, and edited all the text (mind you some things are likely parts of an image) you then need use your quickBMS script to repackage all of your files back into your proprietary archive format and test.
In short, it's not easy. You can do it but prepared to spend weeks, months, possibly even years doing it especially if you're doing it on your own.
That is likely your best option. Myself and another guy over on reddit, jeff7360, have been looking into doing something similar with Criminal Girls Invite Only. We've been looking into pulling the text out of the US version and putting it into the JP version so that people can play the uncensored JP version in english... After we did what i mention above, I still have issues with different parts of the game glitching out (the UI in particular). It just shows that even though something can be done and it works it may break something else.
What playing the undubed version of Odin sphere mind me it was great work translating but sometimes when playing it sometime would be cut out. Or some bottles to appear without text. So I get a feel what graphical glitches might lurking.