God is unchangeable from the Old Testament to the New. If He commanded us to hate then, He commands us to hate now. I also invite Nadir to contrast Our Lord's admonition against hating our enemies with the Psalmist's holy testimony that he has hated God's enemies with a perfect hatred.
The problem on our end is that we're being bogged down by semantics thanks to the unfortunate fact that we are all conversing in English, a damnably inconstant, bastardized tongue if ever there was one. And it seems the English word "hate" is as woefully imprecise as is the English word "love."
If perfect Christian love (agape / caritas) can be broadly defined as "desiring and working for the greatest good for another" (which greatest good we all agree is salvation of the soul), then it would seem that hate (being, in the English language the ostensible antonym of "love") must necessarily mean the exact opposite - "desiring and working for the greatest evil for another" (necessarily, that person's eternal damnation).
If that is the definition of hatred we are working with, then I think we can all agree that no Christian can entertain "hatred" of this kind in his heart and that such "hatred" is irreconcilable with the virtue of Charity. However, as Scripture itself commends and commands certain kinds of hatred, we must infer from that fact that that hatred cnnot be the kind defined above.
So what does Our Lord mean when he tells us to "hate" our fathers and mothers? Well, from what I gather from Traditional exegesis, it simply means "love less" (i.e. love less than God)- but expressed in the typically harsh rhetorical style of Semitic languages.
But what about the Psalm that extols "perfect hatred" for God's enemies? I always contrast this Psalm with Our Lord's admonition against hating our enemies because I think the distinction is a crucial one. Our own enemies are those who trespass against us - the debtors whose debts Our Lord repeatedly demands us to forgive. Why? Because the Christian has died to himself and put on Christ. What does it matter if a man is my enemy or trespasses against me if "now not I; but Christ liveth in me" (Galatians ii:xx)? Therefore the only enemy a Christian ought to have are not his own personal enemies, but Almighty God's; "I have hated them with a perfect hatred: and they are become enemies to me."
So what is perfect hatred? I'd argue that it is not the antithesis of perfect charity, but a vital adjunct to it. It is the casting aside of God's enemies out of holy zeal for Almighty God and out of perfect charity for those who might be harmed by those enemies of God - and out of charity for the hated enemy of God himself, inasmuch as our desire for that wretched soul is not his eternal damnation but, but his conversion and salvation, which might yet be effected through the harsh medicine of "perfect hatred." Take as an example sodomites. These are undoubtedly enemies of God deserving of perfect hatred. If there is an open sodomite in the family do you invite him to your table offer him the comforts of your home where his evil might flourish and infect your innocent children? Of course not. Perfect hatred of a sodomite means to shun him, cast him aside, to treat him as you would a contagious leper, more so because his leprosy will infect and kill souls rather than bodies. St. Pius V exercised that perfect hatred by ordering sodomites to be killed. Was this contrary to Christian charity? Quite the opposite! It was a legislative act of utmost zealous love for Almighty God and perfect charity for the innocent souls endangered by those sodomites - even the souls of the sodomites themselves.
So we can agree then, that the kind of hatred a Christian should have - for God's enemies, not his own - is not one that seeks what is worst for the hated, but what is best. We can therefore say, without any fear of contradiction which might otherwise be stirred within us by the damnable limitations of the English language, that a man who has made himself God's enemy is to be hated because he is to be loved.
With these distinctions made, I think we can proceed with the discussion in this lousy mother tongue of heretical Britannia which we've all lamentably inherited.