Yes, it is. Just copy the content of the hardfile to a Windows folder and then, in WinUAE/CD&HardDrives settings, remove the entry with AmiKit.hdf and add a new entry with "Add Directory or Archive" button where you type:
Device name: AK0
Volume label: AmiKit
Path: <the path to your folder>
Then save your new settings - in Configurations panel mark "AmiKit (Default configuration)" entry and press the Save button.
Just be advised that accessing Amiga files from Windows folder might be slower and less compatible too.