I did this from cmd.exe
as admin
mklink /J "C:\Users\absolute\AppData\Roaming\Apple Computer\MobileSync\Backup" "E:\iPhone DATA\iTunes BACKUP”
and I see confirmation of Junction in cmd and even do
DIR "C:\Users\absolute\AppData\Roaming\Apple Computer\MobileSync"
and see smth like
28.02.2015 10.27 <JUNCTION> Backup ["E:\iPhone DATA\iTunes BACKUP"]
so it should work. But when I try to click on Backup link in File Explorer it brings error Location is not available