For up-to-date information, see SAP Note 519858.
Here is a checklist for preparing to use eCATT:
Maintain table T000 to allow eCATT to be used in the relevant clients.
Patch the systems. For information about which support packages to use, see SAP Note 519858.
Check that the users have the appropriate authorizations.
Install the latest 6.40 SAP GUI for Windows with the SAP GUI Scripting component.
Prepare systems for Web Dynpro testing if required.
Install certified external tools on the local machine of the user. Use the SET_EXTERNAL_TOOL function module to make the required entries in the customizing table ECCUST_ET.
Create RFC destinations (transaction SM59) for target systems.