haha, wow, so your looking for a way to become ticklish, on and off at will ?!?
That's not a technique, more like a super power!
I don't think it's possible to do...
But maybe you should try different methods, and on many different places.
You said the softest feather doesn't tickle you. If doesn't do much for me either. But brushes and fingertips can totally destroy me <3
Of course, you need another person to do all this experimenting for you sadly.
But maybe, that could make it more fun!
Once you find out where your ticklish, and what works.... I doubt you can just "turn it off".
There is ONE way I know of that "decreases" it pretty well in some people.
Next time someone is ticking you (if its possible for you to), don't try to stop them. Instead, place your hand over their hand(s) (that's tickling you). This can trick the brain into thinking its your own hand, because you placed It in the same location where the tickling is coming from.
I learned this from the doctor at a check-up a few years ago. Lol
My waist/sides are VERYY ticklish. So much so, I could not stay still when she examined me
(when they press around the belly area). So she said to put my hands over here as she she did it.
It still tickled me. Lol. But not as badly. I was laughing less, and I was able to control myself from struggling.
Idk how well this works with vigorous tickle-attacks, but it works for the slower kinds.
FIRST you have to either find out where your ticklish, or make yourself susceptible to it.
Well...Good luck with your endeavors!