[plt-scheme] using sqlid in mzscheme 4.1.5

Hello all,
 we have an application running in mzscheme 372, using sqlid to
communicate with Postgres, and plt-web-server. The setup works, but once
in a while we get connection reset by peer errors on larger data
transfers.

 Today I tracked this to a segfault in the mzscheme binary. So I thought
I'll try the most recent version of mzscheme.

 Unfortunately, it looks like sqlid doesn't work in 4.1.5, because it
needs set-car! (it is available in the 4.x planet repository
nevertheless).

 Apparently the preferred alternative would be spgsql.plt, but I'd like
to avoid using it, because:
 - semantics are completely different, would require extensive rewriting
of the application (ouch)
 - TCP level implementation, instead of using the C lib.

 Is there a way to use sqlid in 4.1.5, without rewriting it completely
to use mutable pairs? (even rewriting the application would be more
feasible)

Thanks,
 Mate