[plt-scheme] Question on Syntactic Sugar

I've been working on an "overlay" for Scheme that would let a user
enter a set of extremely dated pseudo-lisp from a puzzle book as
Scheme code in MzScheme.

For the most part, this has been trivially easy, just using (define
old-term new-term). However, I've hit a huge snag.

The old pseudo-lisp uses setq instead of define, and MzScheme throws
an error if you use define within in a definition. What would be the
easiest way to get around this and create an expression equivalent to
(define setq define)?

Thank you in advance,

J.T.