Using Netcool/Impact to perform the function of a OMNIbus gateway is not something you would normally do. But, we had contractual issues that prevented us from using the gateway. Since it was already installed, we decided to use Impact to emulate the gateway. The policies and descriptions are found on the developerWorks Tivoli Netcool Impact wiki:
Don't be intimidated by the size of the policies - the main policy is 150 lines long, but only contains 3 Impact function calls.
The rest is just assignment, very much like the map file in an OMNIbus gateway definition.