The rabbinate is no more difficult to obtain than the Christian ministry. There is, to cite just one example, the Rabbinical Seminary International, which will ease you into that honor. The Seminary does, it seems, require a full day of "intensive" attendance; well, nothing is that easy.
Rabbi Michael Lerner, well known for his espousal of Good Causes and Palestinian demands, was ordained as follows, according his own website:
For ... nineteen years he pursued a course of study that intensified his knowledge of Jewish texts and Jewish mysticism, until he received rabbinic ordination in 1995 from a Beyt Din (a religious court) of 3 rabbis (each of whom had received orthodox smicha).
It would be interesting to interview those three rabbis, but their identities have never been disclosed, as far as I know.
Cyntia Ozick has examined the bona fides, or otherwise, of Rabbi Lerner. Her essay appeared in a pamphlet "Israel's Jewish Defamers," published by CAMERA just now. She has kindly made it available to our readers here.
UPDATE May 28, 2010: Rabbi Lerner bestows his Human Rights prize on (Israel is a war criminal; Hang Blacks) Richard Goldstone. Click here.