There is no need to cross-compile GNU Mach, you can use your native compiler. But you will need to have MiG installed; which can be retrived from CVS or from ftp.gnu.org. As for detailed instructions for doing that, is to be figured out on your own. :-)
Or you can be lazy and download a simple kernel that only has IDE and eepro100 support from http://web.walfield.org/pub/people/ams/gnumach.bz2.
