I have seen a couple of posts on here, regarding people wanting to open the gates of Hell. Depending on what you believe this can actually be done but it would be extremely complicated and possibly dangerous for a beginner. There are many methods to this that will open you up to the infernal energies and I've personally worked one ritual that does this. The ritual that your looking for is Casting the Circle of the Dragon that can be found in The Bible of the Adversary by Michael Ford. This ritual isn't your typical protective circle, it's more or less designed to let many demonic and infernal energies in through the process of invocation. You can use this to work with the daemons that are invoked within this ritual or you can conjure other daemons after the circle has been cast. Anything is possible with this ritual especially if your able to visualize and meditate.
Thoughts and Ideas concerning a new method..
The Simon Necronomicon whether you believe it works or it doesn't does have an interesting method concerning the opening of astral gateways. If one was to create an astral gateway that represents the Gateway to Hell and use a new method that's loosely based on the method within the Necronomicon it might just work. If your familiar with evocation magick, you could evoke a daemon and have it draw the gateway for you on parchment paper. Then later use that gateway during your AP ritual.
I'm sure there are many more ways to this, but visualization and meditation is the key if you want to obtain this.