Capturing an event from a BHO

hi All,
I am working an open source project related called Talkative Browser. The
project's requirement is to make a Web page speak on the event of a toolbar
button click. I have developed a BHO that registers the toolbar button to
the registry and whenever a new instances of the web browser is opened , it
also gets started. It retrives the URL of the current web page. Then it gets
the HTML source code of the same web page. From this it gets the main text
portion alone and gives it to the speech engine which reads the text. This
is working prefectly.
However, I want the speech engine to read the text only in the case of
the Toolbar button(specifically for this sole purpose only)click. I dont
know how to make the BHO detect the button click event. Due to this, my
toolbar button is of no use and my program starts reading once a web page is
opened.
Kindly suggest a solution for this.Looking forward to your respones.
Thanks and regrads,
LMHP
.