SAP GUI authentication through MSAD (LDAP)

Hi,

How do i achieve user authentication on SAP Gui through MSAD (LDAP). Please note, i do not want Single Sign On (SSO). I want following:

1, User login to Windows 7/MAC desktop authenticated from Microsoft Active Directory account

2, User opens SAP Gui client and logs on to ECC instance once again using the user/ID password of corporate active directory.

I do not want SSO where user  clicks on sap gui connection and it automatically connects to instance without asking user credentials.

Please let me know how could i achieve this.

Thanks

Vik