After flashing the router connect with telnet to 192.168.1.1, execute vi /etc/config/network, change the ip address 192.168.1.1 to another of your subnet (example 192.168.1.10), add to file option gateway 192.168.1.1 (your main router ip), add option dns 192.168.1.1 and reboot.
Connect to the new ip, type in terminal opkg update and opkg install luci, open web browser pointing the new ip.
For wireless driver type opkg install kmod-ath9k.
Very simple.
I have the 2740B f1, it work very well with openwrt 12.09. Rock solid, on line from december without errror. With Chaos Calmer wifi disconnect random without reconnect (driver problem i think)
NB Editor vi, key i for insert test, esc after changes, :wq for saving