I made a CryEngine compatible xNormal TangentBasis plugin in my spare time which allows you to calculate the normal maps in the same tangent space they will be used.
You can get the xNormal Plugin right here: CryTB.dll
Supported version: 188.8.131.52502
Please copy the dll into the following place: directory of the \xNormal\x64\Plugins (default directory: C:\Program Files (x86)\Santiago Orgaz\xNormal\3.17.1\x64\plugins)
Start the x64 version of the xNormal
If you are using an older xNormal you will see the following error message:
Press the following icon on the xNormal UI.
Select the "Tangent basis calculators" tab and select the "CryEngine – TangentBasis" plugin.
If you have any problems temporarily delete the dll from your plugin directory.