After windows pe has loaded hold shift and press f10 to bring up a command prompt window.
At a command prompt, type the following command, and then press ENTER:
drvload driver.inf
Notes
Driver.inf is the name of the third-party network driver.
You have to specify the full path and the name of the driver. For example, if Driver.inf is on a CD, and the CD drive is drive D, type the following command, and then press ENTER:
drvload.exe d:\Folder\Driver.inf
Type wpeutil InitializeNetwork
To verify network connectivity, type ipconfig /all.
The drive letter of D varies based on how many partitions are on the local systems hard drive.
https://support.microsoft.com/en-us/kb/923834/en-us