On link http://wiki.openwrt.org/toh/tp-link/tl-wr741nd folow the instructions to soldier and make Rx-TX-GND-VCC leads
I didn't use any voltage divider as suggested on page, instead i integrated max232 in router housing.
http://sodoityourself.com/wp-content/uploads/2007/02/circuit_232.jpg
i took voltage directly from 3v3 power line on board to power max232 circuit and made DB9 leadout on housing. then owe usb-2-rs232 i connected via hyperterminal and boot the device. here the weird thing happened i got weird chars  on screen but i did command mount_root then i did command firstboot and then reboot -f. all led's flashed and i got my router back on default settings.