I can't figure out how to do DLoHi, etc.
Well, the addresses D0/5C00 to D0/67FF are blank space in the RPGe version of the game.
That's because the original Japanese names of monsters were stored there, in a table of 8 bytes per monster name. The RPGe people built a new table with 10 bytes per monster name and stored it in E0/0000.
It's only a theory, but it seems they blanked out the original table instead of leaving it as it or using that space to write new subs because they didn't found how to stop referencing that old table when a monster is captured and it's name is displayed in the menu ("Reply #16" in the "FF5 Bugs & Glitches" thread). To avoid displaying trash in the name of the monster they blanked out the original table and only "blanks" are displayed instead.
Now, that issue is fixed and that means we can use the addresses D0/5C00 to D0/67FF to do whatever patch we want. The only limitation is these patchs will only work after appliying the RPGe translation patch and my [H_noise01] patch. Knowing that, open a patched file to work on it and look for what is the first free address after D0/5C00 to place the new patch in. I think it will be 5C0A, so Hi = 5C and Lo = 0A, but check it by yourself.
Note: I am assuming D0/5C0A because the only patch I know using that table to write code in it is, in fact, the [H_noise01] which uses D0/5C00 to D0/5C09.