What do you mean, "used"? ..You mean, fixed?
My 'bible', "Dictionary of Photography" (19th Edition, 1961, Iliffe Books Ltd., London) Sowerby, A.L.M. (ed), pp 380-381 gives the following formula for hypersensitising film:
Alcohol (90 per cent) - 8 parts
Ammonia (0.880) - 1 part
Water to - 32 parts
"Immerse panchromatic materials for about five minutes. Dry as quickly as possible in absolute darkness and use within a few hours. The speed can often be doubled (increased by 3 degrees B.S.) in this way, but there is a distinct tendency to fog."
It also mentions using sulphur dioxide as an "effective, safe and reliable" method of hypersensitising. Exposed film is loaded into a sprial, then placed into a lightproof container such as a bisuit tim over an open vessel half-filled with a mixture in equal parts of sodium sulphite and glacial acetic acid. Develop normally after 24 hours exposure to the sulphur dioxide. The book reports a doubling of speed or a little more.
I once mistakenly shot a roll of Fuji Neopan SS (100 speed) at 1600 thinking it was a roll of Fuji Neopan 1600 at a wedding. It was pretty much a 'Hail-Mary' attempt, but I did the Anchell-Troop recommended and the negs turned out very well, a bit grainy but I was amazed that not only did it work at all but I actually liked the look. For the effort I wouldn't recommend it, but it sure saved my butt that time.
This is true of the gas hypering that amateur astronomers used pre-digital. H2O2 vapor is a different thing, and with different results. It's been literally 30 or more years and I sure don't remember the details but I came across a method for this back when I was in high school and tried it, getting a quite workable EI 6400 out of Tri-X.
For those who insist on trying hypersenitization the easiest method is exposure to a very dim green light for an extended period of time. The method most often described is the use of a Kodak Brownie safelight with the green cup. A 7 watt bulb is used and half of the cup is covered with black tape. IIRC, the film is exposed at a distance of 8 to 10 feet for a period of several minutes. Afterwards the film is respooled for use. As I mentioned before every film is different and the method must be tweeked for each film.