Create database connection using service account in SAP BI 4.1 IDT

My work change the authentication mode to the databases using Windows Authentication. I have a service account that was created to connect to the DB. IDT offers 3 types of authentication mode:

1. Use BusinessObjects credential mapping
2. Use single sign-on on when refreshing reports at view time
3. Use specified username and password

I created an ODBC connection using the service account. When I tried to create the connection in IDT, I choose: Use specified username and password. When I tried test the connection is failing because it's trying use my account. I tried the connection using the domainname\service account and the password and any way failing. I don't have more idea how I can connect this service account with the DB. Any idea ? Thanks.