Vardhan,
You might have just missed the link. It is not only for the installer, but also for the Sap Adapter 4.6 package. Or, are you looking for the JCO libraries?
After you follow the link as described by Rob, look for the link as below.
–Screen Shot deleted due to limited space–
#Integration-Server-and-ESB#webMethods#Adapters-and-E-Standards