Open the KDE Control Center.
Click on YaST2 Modules.
Click on Software.
Click on Change Source of Installation.
Click on the button at the bottom of the dialogue box, and supply the root password.
When the next dialogue box comes up, click on Add, and add the path to the alternate source of rpm's. When you are done, just go through the normal YaST procedure to install software, and you should see the rpm's listed from the alternate source, as well as the rpm's listed from the SuSE cd's.