The first thing you should say is WHY would you like something like this, so other people can know if it's worth the huge amount of work that it would need to be done.
EDIT: I imagine that you want it so you can use your physical copy on a RetroN 5 or any other similar device with emulators in it.
That's correct. I am wanting to use the JP game on the RetroN 5 because it has slightly different content. I assumed since a script was available that someone had first worked directly from the JP rather than from the American version, but perhaps not.
In that case, just do this:
1. Use the patch on an American copy.
2. Create a new patch using the ROM you just patched as the target and the Japanese version as the source.
My noobiness is showing. Can you break that down any for me? Or provide a link to someone that already has?
My level of knowledge on how to do those two steps stops slightly before step one, after obtaining a copy of the American game. I know how to put a patch on an SD card and apply it with the RetroN 5 (Step 5 below), but that is about the extent of my knowledge.
It seems to me, I need to:
(S1) Either obtain an NA ROM or rip it myself from the physical NA game onto my PC.
(S2) Apply the NA translation patch to (S1) on my PC.
(S3) Rip the JP ROM from the physical game onto my PC.
(S4) Create a new patch using (S3) as the Source and (S2) as the Target on my PC.
(S5) Put (S4) on an SD card to be applied to the JP game by the RetroN 5.
If the above all look correct, please confirm. If not, please correct. And if possible, provide links or information as to how to do steps 1-4, assuming this is not something someone has already done or is something someone else can easily do.