Well...

  (define-syntax assign-group!
    (ir-macro-transformer
      (lambda (x i c)
        (let ((vars (cadr x))
              (vals (caddr x)))
          `(let ,(map (lambda (var val) '(var val)) vars vals)
             ,@(map (lambda (var) 
                      `(set! ,(i var) ,var)) vars))))))

Mind, I haven't tested this, because I don't have CHICKEN Scheme (the dialect this is written in) in front of me, and I may not have matched all the parens on the end, but it should work like this:

  (assign-group! (a b c) (c a b))

Giving you your nice assigment syntax you wanted.

That's the nice thing about Lisps: if you don't like it, you can change it.