I think every hospital is a little different on the way they handle HIPAA. The easiest thing you could do is to sign up as a volunteer, where you'll have to do the class get tested for TB and a couple of other things, then you will do all of the HIPAA forms.
Once you're a volunteer it will make it a lot easier to shadow Docs at the hospital because you already have all the HIPAA forms on file. The Docs that you shadow will briefly explain who you are and and see if it's ok with each patient they encounter and then you are good to go. I did this for a while in the ED, Cardiology, Surgery, Pathology (although here we didn't have to ask the patients, because it's really hard to ask a necrotic testicle or transected colon for permission

), CT, MR, and some other spots I'm sure I'm forgetting.
Plus this way you can volunteer at the hospital too, which I enjoyed.