How to override a Magento administration panel?

I would like to know how have I do to add a fiel开发者_JAVA技巧d in the customer administration at system->configuration->Customer settings panel.

Have I create the system.xml file from the core and paste in the local folder with the same path?

and have I maintain all the content of the file or I can write only the portion interested?

thanks

You should create a module to hold your customizations. Within this module create a system.xml file that only overrides/adds what you want to your configuration section(s).