Guy Perfect has put together a dev kit built around the official Virtual Boy C compiler VUCC. It contains the latest known VUCC version from July 1995, its supplementary tools, IS tools, as well as a Hello World program. The package is rounded out by all new programs written by Guy:
VULK - Virtual Boy Linker Proxy
VUIC - ISX to Virtual Boy ROM Converter
Since the old programs included in the dev kit package are 16-bit, you'll need DosBox to run them. You'll want to add everything under the DEVKIT folder to your path variable. For projects using a makefile, you'll want to use the make that came with Turbo-C.