Hylton took his tally in this season's competition to seven with a first-half double and a third in the 62nd minute before Lee Frecklington pulled one back from the penalty spot after 71 minutes.
Kari Arnason picked up a second yellow card after 83 minutes to kill off the Millers' fightback only for Hylton to ruin his perfect day with a straight red card a minute later.
Hylton opened the scoring after just six minutes with a close-range finish and doubled the Shots' advantage midway through the first half, rising the highest to head home Kieron Cadogan's free-kick.
Having been put through by Danny Rose, Hylton coolly slotted past Andy Warrington after 61 minutes for his third goal of the game.
Frecklington fired home a 71st-minute consolation from the penalty spot after his shot had been handled by Ben Herd.
However, Millers defender Arnason was sent off late on for a second-bookable offence before Hylton was also dismissed for elbowing Jason Taylor.