For my drivers not working in HII: I had to add a line to my unattend.xml (Install Script) under the 'FirstLogonCommand' section to run a batch file. That batch file does several things, but the main thing is it does a WMI query to determine the model and vendor. Then it looks in a folder with the same name as the vendor, and subfolder as model. (Dell -- Latitude E7240). Under each folder I have an 'Install.cmd' which kicks off the Setup.exe for any additional drivers required. I also kickoff the DPInst32.exe and point to the folder that does not have a setup.exe, but seems to load from Device Manager.
DPINST32.EXE /SA /SW /SE /SH /PATH "\\Coreserver\Drivers\Hewlett-Packard\HP ProBook 6450b\HotKey\
This last part may be all you need.