"assisted him on" is correct and usable in written English.
You can use it when you want to say that someone helped another person with a task or activity. Example: "My brother assisted me on my project, so I was able to finish it in time."
Ms. McDaniel then assisted him on a slew of sports movies, helping translate hockey ("Miracle"), football ("Invincible") and basketball ("Semi-Pro") to film.
These maquettes were guides for the engineers, architects and artisans who assisted him on the dozen meticulously detailed studios, houses and utility buildings he clustered around the Goetheanum.
A latecomer arrived — Mr. Carlo's amanuensis, Kelsey Osgood, 25, a Columbia graduate from Brooklyn who has assisted him on two previous books.
Glass assisted him on the pioneering "Cutting Device: Base Plate Measure" (1969), a long irregular stack of lead, wood, stone, and steel elements, with two neat parallel cuts and severed extremities dragged aside at odd angles.
In 1957, in Nice, he met the young, startlingly beautiful German painter Rotraut Uecker, who assisted him on a huge decorative project for the Gelsenkirchen opera house, in Germany, involving canvases and sponge reliefs imbued with I.K.B.
Ms. Friedman Agnifilo had just been hired, Mr. Agnifilo said, and she assisted him on a case in which two deliverymen for the Dizzy Izzy Bagel Store got into an argument over a parking spot that ended with one cutting off the other's arm with a machete.
In "Red," he hires the somewhat shy Ken Thomas Levertonn at Theater Works to assist him on the project.
Assisting him on his journey is Jill Diane, the show's slinky ringmistress, in the guise of Mother Nature.
Without those assurances, records show, Mr. Cioffi would not have been allowed to hire Ms. Francis to assist him on the project.
However, the 67-year-old has his eldest son, Stephen, who resembles Henry Rollins and sounds like early 1990s rockers Dan Reed Network, assisting him on guitar, and Maurice's daughter, Sammy, on vocals.
Assisting him on domestic-policy issues is Oren Cass, a former consultant for Bain & Company, where Mr Romney once worked.The team keeps Mr Romney briefed with memos, e-mails and PowerPoints on topics of the day.
