After a lot of trial and error I finally got it working. Here's a complete INF-file for future reference:
; WinUSB installation file for USB device
[Version]
Signature = "$Windows NT$"
Class = USBDevice
ClassGUID = {88BAE032-5A81-49f0-BC3D-A4FF138216D6}
Provider = %ManufacturerName%
CatalogFile = WinUSBInstallation.cat
DriverVer=09/04/2012,13.54.20.543
; ========== Manufacturer/Models sections ===========
[Manufacturer]
%ManufacturerName%=Standard,NTarm
[Standard.NTarm]
%DeviceName% =USB_Install, USB\VID_1234&PID_ABCD
; ========== Class definition ===========
[ClassInstall32]
AddReg = ClassInstall_AddReg
[ClassInstall_AddReg]
HKR,,,,%ClassName%
HKR,,NoInstallClass,,1
HKR,,IconPath,%REG_MULTI_SZ%,"%systemroot%\system32\setupapi.dll,-20"
HKR,,LowerLogoVersion,,5.2
; =================== Installation ===================
[USB_Install]
Include = winusb.inf
Needs = WINUSB.NT
[USB_Install.Services]
Include =winusb.inf
Needs = WINUSB.NT.Services
[USB_Install.HW]
AddReg=Dev_AddReg
[Dev_AddReg]
HKR,,DeviceInterfaceGUIDs,0x10000,"{ec55ee47-5758-4378-926b-68ed0aec8170}"
; =================== Strings ===================
[Strings]
ManufacturerName="The name of the company producing your device"
ClassName="Universal Serial Bus devices"
DeviceName="The name of your device"
REG_MULTI_SZ = 0x00010000
Replace the Vendor ID (VID) and Product ID (PID) in [Standard.NTarm] with the corresponding VID and PID of the USB you're adding.
Finally replace the ManufacturerName and DeviceName near the bottom with the correct info for your device.
Put this file somewhere on the Raspberry Pi 2, using either SMB or FTP.
SSH or PowerShell to the Raspberry Pi 2 and go to the folder where you put the INF file.
Run the following command: devcon dp_add .\<name of your INF file>
You should see the following result: Driver package 'oem0.inf' added.
Finally restart the RP2 (shutdown -r -t 0
from SSH/PowerShell).
When the RP2 gets back up your device should be listed under "Connected Devices" on the default startup app, and you should now be able to use functionality from Windows.Devices.Usb
to communicate with the USB device.