After more searching and trial and error I am able to get an em0 interface with the macaddr in the OpenBSD guest but am unable to ping my gateway.
Used:
Code:
# sudo sh -c "sudo -C 5 -u user qemu -net nic,macaddr=fe:e1:ab:c0:af:3c -net tap,fd=3 -name openbsd -m 64 -hda /tmp/openbsd50.img 3<>/dev/tun0"