Thanks everyone for your help. I got it working as follows:
Install:
libstdc++2.10-glibc2.2_2.95.4-15_arm.ipk (Repackage it for a sharp rom with ar -x filename, then tar it back up; the install reports an error, which you can ignore)
libpcap0_0.7.2-20031220_arm.ipk
libncurses5_5.0-6.0potato1_arm.ipk
kismet_3.0.1c-20031228_arm.ipk (this method may work with a newer versions too, and when I test this, I'll let you know)
kismet-qt_2.0.0_arm.ipk
Then edit the configuration file:
vi /home/root/usr/local/etc/kismet.conf
source=prism2_legacy,eth0,prism2 (<-- Thanks for this jfv)
(While you're at it: configdir=/home/root/.kismet/)
Then set up a symbolic link as follows, or kismet will complain:
ln -s libstdc++-libc6.2-2.so.3 libstdc++-libc6.1-2.so.3 (the link and the file are in /home/root/usr/lib/)
Kismet (console version) still did not detect my test network until I configured kismet-qt to use Sharp-prism2. Thereafter, kismet-qt immediately detected test network, as did kismet.