The Pukekohe horseman has the drives on Highview Chartom (race 8) and Arden's Darlin (race 7) for the stable, with Purdon on holiday in Australia.
Stormont is now working in the morning on a daily basis for the stable. He will take up a permanent position next month.
Nicole Molander, who is in charge of the stable, is stepping back as she is due to have her second child.
"I enjoy training but I have always loved driving and this is a chance to try and do more of that," Stormont said.
Stormont (44) has driven 1022 winners.
"I drove Arden's Darlin in fast work on Tuesday and she worked nicely," Stormont said.
"The main query for her this week is the standing start."
Arden's Darlin has had two races from a stand for a win at Addington in October.
She finished second to Electrofying Cullen at Cambridge at her last start.
Highview Chartom has been placed in two of her three starts at Alexandra Park since she transferred from Rolleston last month.
She won a heat of the Sires' Stakes at Invercargill in March.
Arden's Darlin could find Caroline's Cullen a formidable opponent in the race for fillies and mares.
Caroline's Cullen, who is off 30m, has won nine races, including three this season.
Simon Lawson, who drove her to a last-start win at Cambridge, has retained the drive.
Stormont also has the drives on Tiger Tina (race 5) and Caesar Court (race 10).
The 2yr-old filly Tiger Tina finished a close second at Alexandra Park on June 11 in her only start.
• Miami H impressively won a heat of the Victoria Trotting Derby at Geelong on Wednesday night.
The Derek Balle and Owen Gillies-trained colt won by four lengths in the hands of Frank Cooney in a 2.02.8 mile rate for the 2570m (mobile).
His time was 0.1sec outside the track record of One Over Kenny.
Avalon Sunset, who has won twice at Alexandra Park for Balle, is now trained by Billy Heads at Waimumu.
