Howto configure virtual network via tap in qemu?

[Andrey V. Elsukov]

Hi!

Somebody know how to configure virtual network via tap interface in qemu?
I try to install FreeBSD 6.0-BETA1 in qemu. My system is 5.4-STABLE. I 
try so:
1. cat /dev/null > /dev/tap0
2. make a ifup script - ifup.sh:
ifconfig $1 inet 192.168.0.1/24
3. chmod +x ifup.sh
4. run qemu:
# qemu -cdrom 6.0-BETA1.iso -hda disk.img -boot d -serial pty -n 
/home/qemu/ifup.sh

tap0 interface is up, i can ping it from my system. But i can't 
configure installation via network.
When i use user mode network stack - it work.

-- 
WBR, Andrey V. Elsukov