Is there a way to boot NetBSD from W95?

I'd like to set up a dual boot machine (os-bs, W95 as default OS) to
switch itself to NetBSD at a certain time in the night, then switch
back. The switch back is easy. The scheduling is easy -- System Agent
can even not switch if someone is using Windows at the time. It's the
booting NetBSD that I can't figure out. Anyone?