Hi Jerry,
You can override the OOB system buttons. I have overridden OOB button before. I think it is part of Application ribbon as we can see the export to excel button everywhere.
Please have a look on below link to get some idea.
http://www.toplinestrategies.com/dotneters/net/disabling-export-to-excel-in-ms-crm-2011-3/
Thanks!