Just edit the .INF file with notepad find the Manufacturer and add ",ntAMD64" like in the following example. Before
[Manufacturer]
%LG%=LG
[LG]
%900B%=900B.Install,Monitor\GSM4A5B After
[Manufacturer]
%LG%=LG,ntAMD64
[LG.ntAMD64]
%900B%=900B.Install,Monitor\GSM4A5B |