/dev/VolGroup00/LogVol02 is the swap volume you want to add):
lvcreate VolGroup00 -n LogVol02 -L 256M
mkswap /dev/VolGroup00/LogVol02
/etc/fstab file:
/dev/VolGroup00/LogVol02 swap swap defaults 0 0
swapon -v /dev/VolGroup00/LogVol02
cat /proc/swaps or free to inspect the swap space.