I'm a guy that do lots of alt-tabbing for streaming purposes and following certain walkthoughs and other tasks that requires me to alt-tab and sadly this game does not come with a borderless fullscreen which makes me sad, and to make it worse, this game supports some odd disappearing mouse cursor when alt-tabbing even with windowed mode is enabled. Is there anyway where I can get a borderless fullscreen to work and to disable this auto hide of mouse cursor on this game so I could alt-tab in and out of the game without problems?

Adding -window to a shortcut target of the /bin/witcher2.exe seems work to some degree. Dunno how much it differs from the ingame setting. Still seems a bit wonky.

There is a post on the Steam forums that links to an app (Windowed Borderless Gaming), that's supposed to work with the Witcher 2.
I have not tried it, so no garanties.

That works http://westechsolutions.net/sites/WindowedBorderlessGaming/

If you get a black screen readd the game or reset the reset the resolution.