If you really want to, you can upgrade to v0.6. It might even work. It will be difficult to get the space savings of busybox with an upgrade at this point in time, but we're working on that as well.
First, back up all of your user data from the ipaq to a safe place!
src v0.6 http://familiar.handhelds.org/familiar/releases/v0.6/base/armv4l/
sh# ipkg update sh# ipkg upgrade ipkg ipkg-confTell it to overwrite /etc/ipkg.conf with the maintainer's version.
Now fetch the new list of available packages, because v0.6 consists of 3 feeds:
sh# ipkg update
sh# ipkg upgrade libc6
sh# ipkg upgrade -force-depends -force-overwrite
sh# busybox --install -s