3DS Font Hacking

1. "Acquire" the 3DS CTR SDK. Google is your friend here, and so is ryanrocks.
2. Use the CTR SDK to convert a Windows font to to a bcfnt font.
3. Use 3dstool to compress the bcfnt font:
3dstool -zvf [FONT NAME].bcfnt --compress-type lzex --compress-out cbf_std.bcfnt.lz
4. Acquire a decrypted CIA of the system font (this can be done either by finding an already decrypted one or by downloading it from the NUS and then using D9 to decrypt)
5. Extract the romfs of the CIA using these commands:
ctrtool --contents=contents [CIA NAME].cia
ctrtool -p --romfs=romfs.bin contents.0000.00000000
ctrtool -t romfs --romfsdir=romfs romfs.bin
6. Replace the cbf_std.bcfnt.lz in the romfs folder with the one you compressed
7. Extract the ncchheader.bin using this command:
3dstool -xvtf cfa contents.0000.00000000 --header ncchheader.bin
8. Rebuild the romfs:
3dstool -cvtf romfs romfs-mod.bin --romfs-dir romfs
9. Make a CFA (CTR File Archive):
3dstool -cvtf cfa font-patch.cfa --header ncchheader.bin --romfs romfs-mod.bin
10. Use makerom to build a cia
makerom -f cia -content font-patch.cfa:0
11. BACK UP YOUR SYS/EMU NAND, THIS IS A PITA TO REMOVE
12. Drop the cia made into /D9Game and encrypt its NCCH using D9
13. Install

Thanks ihaveamac for answering my noob questions