Thompson's ashes have been packed into firework casings and will be dispersed today from 34 different shells fired from a gun barrel mounted on top of a 150-foot high monument.

The monument, in the form of a clenched fist made symmetrical by the addition of a second thumb, is modelled on Thompson's gonzo logo.

"We have never had a request such as this one in our company's history," Marcy Zambelli of Zambelli Fireworks told the Pittsburgh Post-Gazette. "But we respect the request of the family and have actually custom engineered an aerial shell specifically designed to carry out his final wish."

A close friend of Thompson's, Michael Cleverly, said: "They've taken him out and had him pulverised into a consistency that is optimum for the blast, and it'll go straight up. It'll just be taken by the wind and drift around Woody Creek, a place that he loved."

Thompson's widow, 32-year-old Anita Thompson, told the Associated Press that there would be "no crying, no tears, only celebration" at the event, which has been dubbed Hunterpalooza.

"He wanted people to celebrate," she said. "He envisioned it to be a beautiful party. The most amazing people would be there. His friends would celebrate his life. And he was even specific that there would be clinking of ice and whisky."

Thompson, 67, killed himself six months ago with a shot to the head with a pistol. His body was found in a chair by his kitchen table, on which a typewriter had been placed and a page of writing paper had been lined up with the word "counselor" (sic) typed at its centre.

It was a typically enigmatic final word from the inventor of gonzo journalism, the stream-of-consciousness style of writing that was a chief ingredient in the new journalism of the 1960s and 70s.

The age of gonzo officially began with Thompson's account of a drug-fuelled visit to Las Vegas, published in two issues of Rolling Stone, and then released, to great acclaim, as Fear and Loathing in Las Vegas.

Much of today's ceremony and the Gonzo monument has been financed by the actor Johnny Depp, a friend of Thompson's who portrayed the writer in the film version of Fear and Loathing.

The actor, it seems, has drawn an idea from his most recent role as Willy Wonka, the chocolate magnate in Charlie and the Chocolate Factory for today's ceremony.

In the story, six children who find a ticket inside the wrapper of a Wonka chocolate bar are invited to visit his factory. For the funeral the procedure is remarkably similar.

Brian Harvey of Boise, Idaho, found a secret ticket hidden inside the label on a bottle of the Flying Dog Brewery's Gonzo Imperial Porter.

The ticket grants Mr Harvey and a friend entry to the party, as well as transport and accommodation, according to the company's website.

Gonzo Imperial Porter, with a label designed by another close friend of Thompson's, British artist Ralph Steadman, has a hefty price tag and a worthy cause. Bottles of the beer sell for $95 (£53). Only 1,500 numbered bottles have been made, and proceeds from the sale go to raise money for the Gonzo Memorial Fund. The fund, says the company's website, was "set up initially to raise funds for a permanent memorial to Hunter so future generations can ponder the life of one of the world's great mavericks".

But all is not sweetness and light in Woody Creek, the hamlet Thompson made his home. Some residents are emulating the writer's curmudgeonly ways.

Jimmy Ibbotson, another close friend of Thompson's and a musician with one of the acts performing at tomorrow's ceremony, the Nitty Gritty Dirt Band, fired a shotgun at a photographer hoping to take a picture of the cannon from his land.

"He was in no danger," Ibbotson told the Aspen Times. "But he won't come back, you can be sure of that. I wasn't aiming at him, I just wanted to scare his ass. I don't want him coming back here during the event. If you want to print the fact that neighbours are shooting at paparazzi, please do. It might save us a little hassle on the day of the event."

Asked if police had been in touch with him about the incident Mr Ibbotson said they had not. "But I don't answer the phone very much," he added.

After the ceremony, Anita Thompson will attend to her role as protector of her late husband's legacy.

"I'll be working for Hunter the rest of my life," she said. "I know that. I made that commitment, and I'm honoured that I can."

Publication is planned of a third volume of the writer's letters, a collection of short stories and an unfinished novel, Polo is My Life. Anita Thompson also plans "a small book of wisdom" based on the late writer's utterances.

"'Never think you're the smartest one in the room. And never think you're the dumbest one in the room.' Little things like that," she said.

Send-offs to remember

· In April 1997, the ashes of Gene Roddenberry, the creator of Star Trek, were launched into orbit with those of 23 other people. The ashes were part of the payload of Spain's first satellite, launched from Las Palmas in the Canary Islands.

· A fan of the BBC series Dr Who, Tim Haws, from West Sussex, was buried in a replica Tardis made by his brother-in-law when he died last year of cancer.

· Joanna Booth, the wife of a Sotheby's gun specialist, organised a day's shooting for close friends, using cartridges loaded with her husband's ashes. The memorial took place last year at Brucklay Estate in Aberdeenshire and ended with guests bagging several game birds.

· Viking enthusiast Alan Smith insisted his friends send him off in true Norse style. In 1997, the former Cornish docker's remains were put on to a replica of a Viking longboat which was then set alight before drifting out to sea.

· In 2001, the River Clyde in Scotland was chosen for an unusual mass funeral service when the ashes of 50 people who died 35 years before were scattered in a joint ceremony carried out by Catholic and Presbyterian priests. The remains were of those who had laid forgotten for decades in the storage rooms of Glaswegian undertakers.

Jason Rodrigues