I don't think you could do it very elegantly the way the current login box is decentralized. It'd look small and ugly to the deign IMO.
I might be able to do a CAPTCHA-esque type thing like I have on my registration page (
http://audiosubculture.com/forums/register.php) if you would be interested (Just to note, that works better than Captchas and I have had ZERO bots since I did that.), any certain look you want/number or anything?
(No promises, I might be able to help though.)