I have made a rather detailed web guide to dialing in high gain tones on the Pod HD.  I know it's a bit long, but it consists of numerous independent sections - you can probaby skip most of them) to getting the most out of your Pod HD, in regards to achieving high gain tones.  I'm not sure if I want to expand on it any further or not, but I figure it's close enough to being done to go ahead and post.  Here is the introduction:

"The purpose of this guide is to basically provide the details Line 6 failed to provide, mostly geared towards getting high gain tones with the Pod HD 500.  It also applies to the Pod HD 300, 400, Desktop, and Pro; however, there may be a few things here and there impossible to do on the 300/400, or that don’t make sense on the Desktop.

It may seem like I’m treading a lot of ground that the manual covered, but while I’m covering the same topics, I’m providing details on these topics that were not clearly spelled out, which I’ve learned through personal experience or from other members on this forum.

I primarily focus on high gain tones, but I also like some nice clean, classic rock, and blues tones.  Some of the artists I've sought to emulate include SRV, EVH, Satch, Vai, Petrucci, KSE, Periphery, Meshuggah, Metallica, Randy Rhodes, AC/DC, and Opeth. If you can dial in all those sounds, you should have no problem dialing in almost any rock tone you want.  I use all of the traditional rock and high gain amps, with the exception of of the JTM-45."

It also includes sections on guitar setup/hardware, hooking up the Pod in various configurations, defeating clipping/harshness, and various other tips/troubleshooting.

Hopefully this helps some of you out.  If you see any errors or disagreeable content please let me know.

I have made a webpage with sample clips and patches attempting to somewhat emualate some metal/shred artists.  Some are a lot closer to the actual artist's tone than others.  I really just wanted to use all the amps and demo some of my tone-building techniques referenced in the guide.  I am currently in the process of finalizing my latest patches and recording clips for them.  I try to keep the latest versions available for download as I go along.  They should be finalized by the end of April 2012.

http://foobazaar.com/podhd/toneDemo/

Dec. 2012 Update: I have "finalized" (9_9) my patches, but have little time to record a new patch demo.  See the link below for my latest patches.

http://line6.com/support/thread/89897