A detailed installation walk-through can be found in the paper NetBSD and handheld platforms that Alistair Crooks and I presented at EuroBSDCon2004.
Michael Lucas also wrote a paper about installing on hpcarm, but it's applicable to hpcsh as well.
Some photos, mostly different keyboard layouts.
Xhpc works (as you can see on the picture above). Volunteers are welcome to port Qt/Embedded or the GPE Palmtop Environment
You can get prebuilt snapshots (with X11) from NetBSD releng server. They provide all dynamic world that you can actually fit completely onto a CF card!
My todo/wish list.