Quite simply, use this AutoHotKey script. (Tutorial on how to create a script here)
RCtrl::RWin
RWin::RCtrl
LCtrl::LWin
LWin::LCtrl
Works for all but CtrlAltDel.
A workaround for allowing simultaneous CtrlAlt, is to map left to right, and right to left (as opposed to left-left, right-right) i.e..
LAlt::RCtrl
RAlt::LCtrl
RCtrl::LAlt
LCtrl::RAlt
Disclaimer: this answer may no longer be relevant in modern Windows 10/11 versions as it was written originally for Windows 7.