That should do what you need it to do, there are plenty of pages I've seen that will show you how to have this ready at boot up.
iwconfig ath0 essid "MY-WIRELESS"
iwpriv ath0 mode 3
brctl addbr br0
brctl addif br0 eth0
brctl addif br0 ath0
brctl setfd br0 1
ifconfig ath0 up
ifconfig eth0 up
ifconfig br0 192.168.0.2 up
hostapd -dd /etc/hostapd.conf
You'll need to replace "MY-WIRELESS" with whatever you have in your hostapd.conf file.
The IP address that you give br0 will be the IP address that your eth0 has before you start this process.
I have successfully used the code above and have got it working!