Create a plugin hook for pagesetup with a late priority and pull in the breadcrumb, then inject your extra one to the beginning and return the breadcrumb to the page.

Thanks Trajan... How do I "pull in the breadcrumb and return it"?

I think Trajan is suggesting you hook into pagesetup (which is called the first time a view is used) and then manipulate $CONFIG->breadcrumbs directly. 

I don't recommend this approach. All you'd have to do is put a call to elgg_push_breadcrumb() somewhere in an early-loading function or in start.php itself. You theme or site's local customizations plugins would be perfect.