1. Open skype, you will be on this screen1
2. Login with microsoft account using your msn login
3. You will then be at a screen similar to screen2
Select I have a skype account and then it will bring you to another screen asking you if you want to merge your skype and msn account.
4. Proceed to accept it, then login to skype using your msn account and all your skype and msn contacts will show up! Screen 3