There are two ways that I know of to do this (or something like it):
1) You can edit the source breadcrumb code in \admin\skins\breadcrumb.vb. This requires a recompile and, because you are effectually modifying the core, it will get overwritten if you ever upgrade.
2) -my preferred method- add this line of code into your skin .aspx file right before the <dnn:Breadcrumb> line:
<a href="http://intratest/Home/tabid/36/Default.aspx" class="Breadcrumb_Link">Home</a>
(of course, changing the link to whatever your homepage is) and make sure you have "RootLevel=0".
The only time this really looks funny is when you are actually on your home page, or on a subpage below your home page ...then you get "Home >>> Home >> ..." which I can live with.
This has the added benefit of being a skin change and, therefore, not overwritten during upgrades.
Maybe someone more knowledgeable has a better answer, but this works for me.