I'm dying to get started with NetBSD beyond a virtual machine.
I just happen to have an extra ALIX 1D handy which is perfect for this purpose! I'm going to use a 1GB compact flash card as the storage device.
Here's some instructions for installing NetBSD on a compact flash card:
http://bsdsupport.org/2007/01/how-to-install-netbsd-on-compact-flash-for-the-soekris-4501/
But its on a Soekris 4501, not an ALIX, and its for NetBSD 3.99, not 5.01.
I ended up going my own route - I used qemu to install to a virtual disk image created from qemu-img and then dd'd the image to the compact flash card. Worked like a charm I'm happy to report!
Couple of minor surprises:
ftp ftp://ftp.NetBSD.org/pub/pkgsrc/pkgsrc-2009Q2/pkgsrc-2009Q2.tar.gz tar -xzf pkgsrc-2009Q2.tar.gz -C /usr