Please follow the steps below:
1. Download SCM Anywhere Standalone Dreamweaver Plug-in here.
2. Unzip the file and replace RDS.dll with SCMSMXSCC.dll in "C:\Program Files\Adobe\Adobe Dreamweaver CS5\en_US\Configuration\SourceControl".
3. Click Site -> Manage Sites and click Edit in Manage Sites.
4. In the "Site Setup for <site name>" dialog box, go to the Servers tab.
5. Double click the server, choose RDS for "Connect using" and click Settings to set the source control connection info.
Note: In CS5, you are not allowed to check out/in a file by default. You need to check the "Enable file check-out" option at "Site Setup -> Servers -> Advanced".