If it is his page, he can. He needs a link in his page headers like this:
<link rel="shortcut icon" type="image/x-icon" href="http://wp.traceyroad.com/wp-content/uploads/2014/07/design8-3_plain-gray-01-150x150.png">

(to your own image, of course)

Thanks, that's changing the favicon - how can I do it without changing the favicon?

Example: Twitter's favicon is a bird (http://i.verringer.com/185653.png) but their start page icon is http://i.verringer.com/185705.png

Hi there,

I recently changed my start page to the new one, how can I change my websites so it doesn't display the default?

Example: http://i.verringer.com/232415.png (my site is mc-market). Thanks.