I've been looking for a panel that will fit an open 5.25 or floppy sized slot and which provides front panel access to firewire and USB ports. I've found this item at CompGeeks, but it says it is for "AT compatible" systems (whatever that means).
I would think that it would work, But dont hold me to it.
I have looked at FrontX they let you pick what ports you would want on the front, You may want to look there also.
I can't see any reason why it would not work in your case or anybody's case. All you need is a free 3.5" drive bay and a hole in the back of your case to snake the cables to the usb connectors on the back of the machine.
AT/ATX has nothing to do with it. Looks like you found what you need.