WB: COPY C:\WINDOWS\SYSTEM\KBDFLEX.DRV C:\WINDOWS\SYSTEM\XXXXX.DRV WIN WL: COPY C:\WINDOWS\SYSTEM\XXXXY.DRV C:\WINDOWS\SYSTEM\XXXXX.DRV WIN
If WB and WL reside in some PATH-ed directory, you can start the Bulgarized Windows with WB and the full-latin Windows with WL.