I'm pretty sure you can only get access from one of the underwriting companies like MS, GS, JP Morgan, Citigroup, etc. that offer it to their wealthy clients.
It's worth to note that the IPO system is "rigged" against private investors. If its a hot deal, the banks load themselves up before it hits the market, leaving nothing for private investors. While if it's not so hot or its a bad deal (see Facebook), the banks still wanna get their commission, so they push the IPO on their clients.