Client Side Question

I have a Control that is installed and registered on the client machine. It is embedded in a web page and when the page it accessed it loads the control IF the client has the control installed properly.

I want to access the control classes through scripting in the web page. For example: I want to set the text property of a text box to read "Hello World!" and change it to "Goodbye!" by clicking a a link on the web page.
Something like - onClick="Control.Text = 'Goodbye';"

I have my property set in my code and currently change them with the PARAM tag.

Any suggestions?

Thanks
ML