For writing homebrew on NDS, you will need some of these:

• devkitARM
• libnds (compulsory)
• dswifi (yep, use wifi-module)
• PAlib (makes life easier)
• libfat (writing on your CF/SD card)

Don’t use the ebuild available somewhere on gentoo packages, as it uses devkitarm19 which is already deprecated and does not work very well with DSerial. devkitarm20 is fine at the moment & nothing to compile neither.

Found a great bash-script for installing the devkitpro toolchain (unfortunately, after all installation-hassles):
http://palib.info/forum/modules/newbb/viewtopic.php?topic_id=1647