I am using kvm and qemu on my Linux host.

/usr/bin/qemu -boot c -m 256 -hda '/home/yao/workspace/vm/qnx/qnx632/qnx632_x86' -cdrom  '/home/yao/workspace/vm/qnx/
qnx632/newbios.iso' -net nic,vlan=1,macaddr=00:01:02:03:04:07 -net tap,vlan=1,ifname=vmtap1 -localtime &

my host 
vmtap1    Link encap:Ethernet  HWaddr 00:ff:48:db:fc:2e  
          inet addr:172.20.0.1  Bcast:172.20.255.255  Mask:255.255.0.0
          inet6 addr: fe80::2ff:48ff:fedb:fc2e/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:8 errors:0 dropped:0 overruns:0 frame:0
          TX packets:46 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:500 
          RX bytes:2736 (2.6 KB)  TX bytes:6298 (6.1 KB)

so I only ifconfig en0 172.20.0.2/16 in my qnx target then route add default 172.20.0.1.
if you have nat setup in your host then you should be able to access Internet via your Linux host.
what is your host interface macaddr?

Yes, we managed to setup a network.

We are using kvm, and our line to boot is like this:

kvm -m 512 -net tap,script=/etc/kvm/kvm-ifup -net nic,model=ne2k_pci,macaddr=52:00:D4:85:30:00 -drive file=/var/lib/kvm/
qnx/qnx-momentics.raw


Then, modify qnxbasedma.build in the guest as documented here: http://community.qnx.com/sf/wiki/do/viewPage/projects.
qemu/wiki/NeutrinoAsGuestInQEMU and it should work =)


Hope it helps