Wow they look just like the wii ones
Anyway Time for the guide
What you will need:
1. NDS Header (used to extract everything at once)
2. NDS Top system (used to import)
Both the above can be replaced if there is a program that does both
3. Photoshop (makes images)
4. Hex Editor (you'll see
Step One Extract Files
Use NDS Header and open the ROM go to "File System info" and click "Extract Content"
Step Two make images:
Make the image it must be 19x16 and thats about it. Go to File-->Save for web and devices. there make sure it is set to PNG 8 and lower the colors to try to match the file size with the original for example if the original was 661 bytes try to go for 660 or 659. (The File size is displayed near the bottom of the window)
Step Three Hex Editing:
Now that you have the file open THE PNG YOU MADE in a hex editor add 00 to the end till the bytes are like the originals. for example in the original was 661 bytes and your file is 659 bytes you will need to add 2 "00s". When you try to save it the program will tell you that it will add +X bytes. ( at least mine does)
Step Four Import:
After you finish the file open the ROM in NDS Top System and import the new file over the old one. The program should say imported sucsessfully unless you diddnt add enough bytes or to little.
Step Five Do it again:
You will need to do this with every other PNG you will edit.
I kina just wrote this guide just now if you dont feel it's that understandable Ill make another with pictures and everything