Comment 9 for bug 897786

One way I know is by using the mini.iso image (netboot) which exists in a non-pae flavour at:
http://archive.ubuntulinux.org/ubuntu/dists/precise/main/installer-i386/current/images/netboot/non-pae/mini.iso

I know some flavours of Ubuntu chose to ship with non-PAE by default, using one of these (probably xubuntu and lubuntu) would work too.