You can use an image widget to add the button: http://en.support.wordpress.com/widgets/image-widget/
Thanks for the response.
Are you suggesting that the image widget will allow me to have embed code?
Cause when i looked the link you shared, it just mentions linked URL.
I’ve been able to achieve the look & feel i wanted for the button, I just need to add my own custom HTML + JS functionality associated with that button.
If thats possible with the image widget, i’ll surely give it a try.
The image URL allows you to add an existing image (eg the button) and a hyperlink to it. You can take a screenshot of the existing button, upload that to your blog’s media library, and add that as the image to your image widget.