SRFI 41's reference implementation has two variants, one for R5RS and one for R6RS. MIT Scheme is boycotting R6RS, so you should use the R5RS version.
I haven't used MIT Scheme, so I can't say further beyond that. From what I see on their home page, MIT Scheme also appears not to have a module system, so you probably need to just save that file to your project directory and load
it in, the old-fashioned way.