1. Put a ttf on a SD/CF/... card
2. Create a symlink in /usr/share/fonts/truetype/ to the font dir on the media card
3. Run fc-cache in /usr/share/fonts/truetype/
4. Optionally edit /etc/fonts/fonts.conf or local.conf to set loading priorities
If the above sounds too cryptic for you: please don't try

We have plans to add support for your own fonts in the future.
Also: you can request a package with extra Chinese fonts. All Chinese iLiads receive it by default. It adds two more Chinese fonts (but takes quite some space on the internal root filesystem).