Tekezo has updated build-dreamcast-cross.sh, which is a script to build a Dreamcast cross compiler. You can get it from the Expanded NesterDC site:

Changes

• refine build process. It shorten building time about 10 minutes.

Tekezo had this to add:

“This script seems failed on cygwin by some mysterious reason. If you succeed building cross-environment on cygwin. mail me please.”