A port of the portable SRFIs project specifically designed to integrate with Chez Scheme has been released, by me. :) I haven't been able to make a clean patch upstream, but I intend to do so soon.
Not all of the functions are as optimized as I would like, but I don't believe I have altered any of the existing files, and only added Chez specializations. More information can be found on my gopher server. You can also downloaded the latest development work using the Monotone server found at mtn.sacrideo.us, branch us.sacrideo.srfi.