As almost everyone knows the company called Quality Sim is making a payware 757 but also has the beta version out and it has been out for a while. I decided to see if this bird would work in FSX or not....it does!
http://www.qualitysim.com/

Installation instructions:
Run QW752beta.exe
Click next until you reach the installation directory page.
Click the "..." button (AKA browse button.)
Create a temporary file for it. (i.e. C:\Users\yourusername\Downloads\QWSIM)
Select that directory and install.
Take the "QualityWings 757-200" folder (inside the aircraft folder) and place it in your Program Files\Flight Simulator X\SimObjects\Aircraft folder.
Now got into the QualityWings 757-200 in your simobjects\aircraft folder and open the panel folder.
Open "panel.cfg"
Replace the "4" with an "8".
Save it.
Go into the sound folder and do the same thing.

If you have the captain sim 757 or even a working POSKY 757-200 panel, I would suggest going to that aircraft and copying the panel folder of that and using those panels instead. I use the CS757 panel, works perfectly. Same with sound.