I too am looking for a driver that works in WinPE. We just tried all 5 drivers in the SCCM package (http://support.lenovo.com/us/en/downloads/ds102112) and none of them gave us an active NIC.
1. drvload <name>.inf
2. ipconfig
3. netcfg -winpe
4. ipconfig
We are using 9.6 SP1, which uses WinPE 5.0. For that version of WinPE, we use the Windows 8.1 drivers, right?