If you are doing this because of a broken connector (?)
I found this video -
That one decides that replacing the entire antenna (and doing surgery on the display assembly) is not worth the risk of an even more expensive repair/replacement of the display assembly. And the person doing the repair states he is Apple certified, and even so, decides against that risky repair. He simply attaches another antenna, which gets tucked under the I/O board. So, not like factory, but a usable, useful mod.