Dir-300 as Wifi repeater

I have an AP in my house which broadcasts our wireless Internet signal throughout our house. Unfortunately there is a spot in my house where the signal is not received. I have a spare dlink dir-300 router which I installed custom firmware on (dd wrt). Can someone please help me use it as a wireless repeater. I want it to boost the signal of my other router. Dd wrt has a repeater function, but my router is an atheros chipset so it is not native on my device.
P.s: I don't really want some cheap wifi booster made of tinfoil :p .
Thanks in advance,