[KissLick]

Yep, I meant to (on user's side):

1. Open de_dust2 with hexeditor and save checksum
2. Decompile de_dust2
3. Edit de_dust2 with Hammer and replace all taxtures to glass textures
4. Compile de_dust2
5. Open compiled de_dust2 with hexeditor and change checksum to saved checksum from original de_dust2

I would be very surprised if it's possible, this would give you very basic form of WH...