Go to your "My Account"
Click Affiliate Settings
Click the Edit Button next to the Google Adsense Box toward the bottom.
You will then be asked if you have a current Adsense account. (which you shouldn't)
Then select No, input the email address that you will be using for your adsense account and submit it.
You will also get a verification email from HP asking for permission to have access to your account. This is mainly so that you can check your Adsense directly from the HP site, this is required.
That is about it, I hope it helps...Keep in mind Google is taking upwards of 4-6 weeks to approve new accounts so don't freak out when it says it will be reviewed in a week, and isn't.