How to map keyboard shortcut "TAB"?

I would like to map the keyboard Cmd-TAB as Alt-TAB in my Guess OS. However, the problem is, in preference-> Keyboard & Mouse, whenever I typed TAB key in the text box at "From:", it just switch focus to the next box (To without entering the TAB key i just pressed. Anyway that I can enter "TAB" key in the "From:" text box?

 

Use Alt+TAB first

Then you can unclick the Alt, etc.

 

Anyone have an answer to this one? Paey-LunC question was not correctly answered. I want to create a new Keyboard shortcut that utilizes the Tab key. When I press Tab it just "tab's" to the next field instead of capturing the Tab keystroke.

 

Works for me. Press ALT-Tab in the From field. Then, unselect the Alt modifier.

 

Thanks Mr. C. I wasn't using the right side of my brain.

 

Thanks for the answer to this question - it is a bit tricky/fiddly to find how to do it..

I have successfully managed to map the shortcut.. But the behavior is that when I am in Parallels and hit Cmd+Tab, it brings the Windows Alt+Tab application switcher... as well as the Mac one!
So every time I hit tab both OS cycle through to the next window. Anyway to "disable" the Cmd+Tab doing anything in Mac O while the Parallels desktop is active?