I've converted Humanity icons and made the package which updates boot icons. Fake screenshot attached (rEFIt can't make screenshots by default).
You can download mac installation package from https://edge.launchpad.net/refit-humanity/+download
Bug reports, suggestions etc can be posted here or on launchpad https://edge.launchpad.net/refit-humanity
Like it? Hate it? Say it?
I'll blog about it on Ubuntu Planet as soon as wordpress.com gonna come back out of downtime.