Dir 655 as repeater

I know that there are lots of posts about this, but I am still not certain about something.

I know that DIR 655 does not support being a repeater naturally (via admin panel). I read some methods that describe how to do it, but all of them seem to require connecting a LAN cable between the MAIN router to the DIR 665 that they want to use as a repeater.

My question is if it's possible to achieve the same but without connecting the LAN cable between DIR 655 and the MAIN router?
So in other words, the DIR 665 will just repeat and extend the wifi signal..

Thanks!