Turretin on Double Imputation via Witsius...

X. These things are prosecuted excellently by and large by Turretin, on the truth of Christ's satisfaction, part II. sedition xxxiv. Neither do I think it will be disagreeable to any, if his words be here recited. 

"As we are said to be made righteousness in Christ, by imputation, because on account of the righteousness of Christ, apprehended by us through faith, and imputed by God, we are pronounced righteous before him; so in like manner, that the nature of the opposition may appear, he was made sin for us by imputation, because our guilt, wherewith we were bound in the judgment of God, was laid upon him as our Surety, that he might suffer the punishment due to it. Augustine expresses himself most excellently in his Enchiridion to Laurentius, chap. xli. He sin, and we righteousness: not our own, but God's; not in ourselves, but in him. As he was made sin; not his own, but ours; not in himself, but in us. 

Thus, indeed, by a wonderful exchange, he took our evils upon himself, that he might bestow his benefits upon us; received misery, that he might grant mercy; received the curse, that he might make us partakers of the blessing; received death, that he might confer life; received sin, that he might impart righteousness. This exchange on both Sides agrees in the following things; first, that in both, something foreign is by the estimation of the Divine judgment transferred to a person: which translation is not an error of judgment, but a certain appointment, whereby on account of something done by another, something is assigned to thee, as if thou hadst been that very person from whom that action arose. On account of our sin, death was inflicted on Christ, as if he himself had sinned; and because of Christ's righteousness, life and the inheritance are conferred on us, as if we had been righteous, and had fulfilled the law. 

Further, that on both sides there behoved to be a connection between these persons: for our sins could not have been imputed to Christ, unless he had been united to us both by the bond of the same nature, and a voluntary suretiship: neither could his righteousness have been imputed to us unless we had become one body with him. Yet they differ far in this, that the imputation to Christ is according to justice, to us according to mercy. Sin was translated to him, but to be abolished; righteousness to us, but to be preserved; the curse to him, in order to be swallowed up; the blessing to us, with a view to be continued; pollutions to him, that they might be cast into the depths of the sea; the new robe of the first-born to us, that it might be put on. Hence it is, that we can be called truly righteous, and the sons of God; but Christ cannot therefore be called either a sinner, or a son of wrath: because he neither had sin of himself, nor did the wrath of God abide on him, but only passed over him." 

So far Turretin: to which things, expressed with equal solidity and elegance, I subscribe with heart and hand.

CONCILIATORY, OR IRENICAL ANIMADVERSIONS, On The Controversies Agitated In Britain, Under The Unhappy Names Of Antinomians And Neonomians. By Herman Witsius, D. D., Chapter II.