Well, if it is supported.. it'll be by the NetBSD/hpcarm port.
http://www.netbsd.org/ports/hpcarm/
http://www.netbsd.org/ports/hpcarm/howto-use.html
These devices appear to use an XScale PXA255 (ARM) processor, have around >= 64M of ram.. but sometimes less.
It's pretty interesting reading about the fact that the OS used on these systems (WinCE/PocketPC/Mobile) don't fully utilize the MMU and thus an OS like BSD or Linux can be loaded and write over it in memory.
If a "console" environment is what you want, SSH/telnet clients exist for the native Microsoft OS.. alternatively find a distribution of Linux for the iPAQ/arm.
I can't guide you, or even say if the hardware is supported, but be sure to post details of your adventure.. some of us enjoy reading about it.