Thorman will require acupuncture in a bid to cure a hamstring injury, while the Giants' other stand-off Paul March is out for the season with a serious knee injury and possible replacement Kevin Brown is ineligible for the game.
Hemmingway has made only six engage Super League appearances so far this campaign but impressed Thorman during the 14-10 loss to Wigan on Friday night.
"Tom is a very talented player," said Thorman. "He had a good game on Friday to sort of shake the cobwebs off. It was his first Super League game for a while and he played very well.
"Defensively, he was very strong and he took the team around the field well without the likes of me and Brad.
"He really put his hand up. Whether he's named in the twenty, we'll have to wait and see but I'm pretty sure Tom would do a good job for Huddersfield."
The chances of Thorman playing on Saturday have been declared "extremely doubtful" by coach Jon Sharp, who also has to deal with injury worries over Paul Reilly (neck), Brad Drew (calf), Stuart Donlan (quad) and Martin Aspinwall (groin).
"My disappointment, if I don't play, is going to be another guy's opportunity to make some history," continued Thorman.
Hemmingway's inclusion may rekindle memories of 19-year-old Peter Ramsden who scored two tries and lifted the Lance Todd trophy in Huddersfield's 15-10 defeat of St Helens in 1953.