Look for something called bicalutamide - it's the successor of cyproterone acetate, except with fewer side effects (much less likely to cause liver damage for example). It's a anti-androgen pure and simple (unlike spironolactone, which is a diuretic with anti-andogenic properties and also has more common side effects).
Bicalutamide is usually used in prostate cancer, but you can go lower dose and still get feminising effects. It complexes with the androgen receptor and causes it to migrate to the nucleus where it can no longer be touched by any of that nasty T or DHT. In addition, as a special little bonus, it also inhibits the metabolic breakdown of estrogen so you get more of that as well. 😀