There are many ways this can be played on stage.
The sexism in the play is in Padua, itself. Kathrine and Bianca live in a male dominated world. Kathrine is an independent woman who knows her own mind. She knows the eligible batchors in her world and isn't impressed. She will not go willingly to the slaughter, so to speak. If she can prove to be so unpleasant that nobody will want her, it is better than being married to a rich old man or fool. Her sister, however, trusts that her father will find her a suitable match.
The key to understanding the relationship between Kathrine and Petruchio is their first meeting. In the sexually charged dialogue, Kathrine has found a man worthy of her but her pride will not let her submit easily.
It is in the sun/moon scene where the two get on the same page. They both realize how much fun they can have if they join forces. When Kathrine comes when Petruchio calls her in the final scene, it is their joke on the rest of them. Does she mean what she says in her monologue? Most certainly, she does. In the church, she was forced to say the words but now she says them out of love. What is most importat is how Petruchio reacts when she kneels down to him. If he takes her hand and they rise together, we have equality in their relationship which is what I believe Shakespeare intended.
Neither Kathrine nor Petruchio is "normal" by Padua standards. It s also interesting to note the the play ends on a trochaic inversion, where the energy dies at the end.
Like a lot of Shakespeare, the meta-message in Shrew can depend a lot on staging.
In the Royal Shakespeare Company's most recent production, Christopher Sly (who begins the play with a kind of framing device, but then never returns at the end) stays on stage through almost the whole play, and the staging seems to suggest that the whole play might be his fantasy. If you imagine that the unfair relationship between Kate and Petruchio is based in the imaginations or fantasies of a drunk man, the story can be seen as a criticism of men's fantasies of dominating women. You can read a review of that production here: http://www.guardian.co.uk/culture/2012/jan/26/taming-of-the-shrew-review
Another great production was put on by Propellor Theatre, back in 2007. Propellor is an all-male company, which makes for some interesting and original (or at least, unconventional) performances when sexual politics come into play. I actually saw that one, and when Kate is played by a man, it adds an extra dimension--is Petruchio's macho cruelty really aimed at Kate, or at a part of himself or his maleness that he percieves as weak?
You can also check out eNotes' page on themes in Shrew here: http://www.enotes.com/taming-of-the-shrew/themes -- the first one is on 'gender roles', which is definitely relevant to your question.
It is, of course, easy to argue that this play does show a great deal of sexism. After all, the ways in which Petruchio treats Katerina would be extremely offensive if done today. In addition, Katerina seems to come around, by the end of the play, to the idea that male dominance is the natural way of things. This is surely sexist.
However, many critics feel that there is a subtext to the play. They point out, for example, that Shakespeare portrays Katerina in something of a positive light and gives explanations for her "shrewishness." He shows her to be intelligent and strong. He lets us think that her bad temper may be due to her father's clear favoritism towards Bianca. By doing these things, Shakespeare seems to be trying to get us to sympathize with and to like Katerina. This would seem to turn the message of the play on its head because it argues that women in fact can be men's equals and that women who do not act in the "right" ways may simply be lashing out against the way they are being treated by society.
If there is sexism in this play, I tend to think Shakespeare takes an untraditional approach and shows women controlling men--beginning with Bianca's manipulation of her father. Katherine and Petruchio's relationship is complicated, but they do end up on somewhat equal footing, in some kind of balance by the end. Whatever they have, though, it is preferable to the other two marriages we see at the end of the play. While Lucentio and Bianca presumably marry for love, it is clear that Bianca is the stronger-willed of the two and will get her way--as she always has with her father. The Widow clearly browbeats her husband, Hortensio, and there is little doubt he is doomed to be her doormat for life. There is no evidence that either pair will ever achieve an effective balance in their marriages, whereas Katherine and Petruchio seem to have achieved it in a relatively short (though painful) time.