Trial Balance or any other default Report - Add custom Button

Hi all,
I have searched the groups for a small extend on existing Query Report / Script Report …
I would like to add a Custom Button (Extend) to Trial Balance or any other Script Report .
To achieve (Exportar XLS) this i had to create a local Trial Balance (copy original) and add the button but i wonder if there is no other way like in hooks “query_js = …/trial_balance.js” to extend existing like we do with Docktype and other JS files.

Hi all,
Does anyone knows how to extend JS Report?
Need to add and extra button on Accounts Receivable.