Happy New Year.
Ah yes, Mystic Square's .TX2 files are very tricky. The corruption of those files can lead to some...
interesting results.
There might be an easier way to edit those files, but here's how I did it:
First of all, make a copy of the original .TX2 files - it can be helpful later on for reference.
I would recommend preparing an already aligned script in advance (the rules are the same as LLS - 3 lines of 30 bytes per line, custom 2-byte graphics/Gaiji characters should be placed in odd-even byte pattern (e.g.: 1st & 2nd, 11th and 12th, 29th and 30th bytes of the line, etc.)).
Open _DM00.TX2 with WinHex.
Replace the original script with translated text, one line at a time. Pay close attention to the number of bytes for each line (30 max).
If you can't type or paste Korean (or Japanese in this case, as you use a modified font) in WinHex, there is a way around that. Download
GetMyHex by Ryusui and paste the first line of translated Reimu's dialog in there. Now you can copy the hex values of that line and paste them into the .TX2 file in WinHex. Ctrl+V it where the line should be (select ASCII Hex when asked), and delete the original Japanese hex values of that line. Be careful not to delete any Gaiji characters or commands though.
You can find the list of Gaiji characters' hex values (0CXX) in the Pastebin link I posted earlier:
http://pastebin.com/Uq8uA1N6If for some reason you need extra space for a line, you can use Edit->Paste Zero Bytes option and replace zero bytes with text or commands.
Here's some commands that can help you with inserting new lines or text boxes, and better understanding how .TX2 files work in general:
0B0D - next line
0BFF0X0D - next text box (0X: 00 - player, 01 - boss)
0BFF0X020Y0D - next text box (0X - player/boss switch, 0Y - portrait change)
Portrait codes:
Reimu: 00 - normal, 01 - wink (gohei wield), 02 - smile, 03 - sweat, 04 - angry
Marisa: 00 - normal, 01 - raised hand, 02 - angry, 03 - sweat, 04 - lightning
Mima: 00 - normal, 01 - closed eyes, 02 - angry, 03 - sweat, 04 - rapeface (unused; I made some use of it in the English patch. If you are curious and want to use it as well, check out the modified files from the English patch.)
Yuuka: 00 - normal, 01 - smile, 02 - smile & closed eyes, 03 - sweat
Sara: 00 - normal, 01 - raised eyebrow, 02 - closed eyes, 03 - defeated
Louise: 00 - normal, 01 - open mouth, 02 - wink, 03 - defeated
Alice: 00 - normal, 01 - open mouth, 02 - defeated
Yuki & Mai: 00 - normal (Yuki), 01 - normal (Mai), 02 - smirk (Mai), 03 - angry (Yuki), 04 - defeated (Mai), 05 - defeated (Yuki)
Yumeko & Shinki - 00 - normal (Yumeko), 01 - raised hand (Yumeko), 02 - defeated (Yumeko), 03 - normal (Shinki), 04 - raised hand (Shinki), 05 - both hands raised (Shinki)
EX Alice: 00 - looking in the book, 01 - open mouth, 02 - smile, 03 - defeated
Now that you've edited the script, let's finish it up with one last thing. See those first 10 bytes in the very beginning of the file? Those are pointers, 5 reversed byte pairs. The first pointer is always 000A (0A00) - the beginning of Reimu's dialog. The second pointer is the end of Reimu's dialog (and beginning of Marisa's), the third pointer is the end of Marisa's dialog, the fourth pointer is the end of Mima's dialog, and the fifth poiner is the end Yuuka's dialog (and the end of the file).
All you have to do is compare the location of the pointers in the original file to your modified file, and type in the location of the pointers (reversed) at the beginning of the file. Here's a comparison image of the original file and file from the English patch:
http://imgur.com/pnuWWu6And that's it. What a nightmare, I know.
Good luck!