Alter SAP standard code not working

As you have mentioned you require access key for the change to be complete, but this key is mapped to SAP specific installation. In short, you need to retrieve this key from the SAP.

I would still suggest not to go for the change. You can seek other alternatives for this. You can analyze the feasibility of implicit enhancements usage. The reason I am recommending alternatives is whenever you would have an upgrade in SAP, you would require a change which is cumbersome.