Adding text 'on demand' to a textarea or rtf

I am developing a more useful email sender in a CRM, and it would be really helpful if someone could add some text by simply clicking a button. In my daily email reading and writting routine I am asked too much times the same information: Eg: Paying methods, weekly schedules, etc. It would be great if with some button we could add text to a textarea, and better if it would be added to a RTF apliccation.

I have tried a lot of RTFeditors… and i am currently using openWYSIWYG.

Do you know if there is a way to add some text via javascript, flash, or other language, to a textarea or RTFeditor?