Superfox,
Very interesting comments.
1. It turns out that if you want to immediately generate gross piti virtually immediately once you have access concentration, you can do metta. I just sorta imagine the in-breath is taking pain away from some "person" in front of me and the out breath is delivering health-energy to them. This is kinda useful since the gross-piti jump starts me a bit when I'm suffering from sloth/torpor/tension.
I also have found this to be true. Metta was my own breakthrough in being able to generate piti. I was very surprised by this -- as I was extremely skeptical of the value of Metta. When I sit with my local Shambhala group they sometimes instruct us to do Metta (They call it Tonglin) and I have always just faked it and continued to count my breaths. But once I finally gave Metta a shot Piti started to arise.
I have a very difficult time generating Metta do to my own mental defilement. I started with a sick kitten (per Ajahn Brahm's instructions), as I am I a cat person--that sort of worked.
BUT
what really worked for me is to think of the most pathetic person I could from reality television. As crazy as it sounds this was the breakthrough technique. I was once watching this program and there was this older man showing his home kitchen. The host asked him, "Do you have a lot of parties here with your mates?" He just replied, "I don't have any mates." I don't know why but thinking about this always sets off my Metta practice like gangbusters.
To generate Piti now I only need a bit of access concentration
The other breakthrough technique was following Ajahn Brahm's famous simile of the cup: https://www.youtube.com/watch?v=Y-QlSW5KwxI I have seen this mentioned many places on this forum. However, I never know exactly how to interpret this. Basically, I do some counting technique then take a break and just let the mind settle, then go back to counting until it feels to course. I Let the thoughts ramble and spin out on their own while I very very gently watch the breath.
I then sort of will the Piti to arise, it feels like relaxaing a muscle in the specific places on my body that piti has a tendency to come out of. It's always either the upper back, the top of the head, or the 3rd eye area. Although occasionally there is a vibration like feeling over the entire body. Right around the time I can do this a very dull nimitta appears.
It feels like I am opening the poors of my skin where the piti comes out of. I know that sounds absurd but it is the closest I can come to describing the sensation. Since piti was only arising from very specific areas I went to a Qi Qong teacher to see if he had any advice. He described this as the upper Dan Tiem (sp?). Doing some standing meditation exercises, with open hands in front of these areas has also helped piti arise more strongly.
The other technique that helped me generate piti is even more eccentric.
I was practicing a technique for a while to help me deal with my social anxiety problems in business. It is from a wonderful book called "The Psychology of Call Reluctance" By George Dudley
Anyway, the technique is called "threat desensitization". But to prime the technique you first practice making a very tight fist while you hold your breath.
You close your eyes and pretend you are looking at your fist through binoculars. You also imagine that there is a button on top of the binoculars. When you press this button the word "SET" appears over your visual field. You then slowly let out your breath, and slowly relax your fist. When the fist is fully relaxed and your breathing returns to normal, you gently touch the forefinger and thumb.
In the therapy you are then just supposed to visualize a threatening situation and then say to your self "set --- relax". By applying this technique to my normal meditation, (just saying set--relax once I am close to access concentration) it sets off piti and sukkah as well.
In terms of Scott's comments about generating pleasant sensation in your hands. It would be difficult to imagine having piti come from my hands as I have never experienced piti being generated in the extremities or below the upper back at all -- only occasionally when I have a fully body vibration type feeling.
I understand Leigh Brasington first entered Jhana through piti generated by pleasure in his lower back. I have had piti arise from adjusting my seat before, the pleasurable experience seemed to just translate into having the actual piti feel like it is coming from the upper back per my usual experience.
I hope this is at all helpful.
Best, Luke