Manager Keith Hill was dealt a blow late on Thursday after injury to Kenny Arthur ruled him out of the trip to the south coast this weekend.
Arthur joins reserve keeper Matt Edwards, who is currently sidelined with a fractured wrist, leaving Hill without a professional goalkeeper in his squad.
Rochdale have consequently taken advantage of a seven-day emergency goalkeeper loan. And once independent medical evidence proving Dale's two goalkeepers are injured is provided, Lillis will join the rest of the squad.
The goalie, who has just recovered from an ankle injury, is no stranger to the league having spent time out on loan with Grimsby and Notts County earlier in the season.
Meanwhile, Frenchman Manga joins Dale on non-contract terms until January.
The 21-year-old, who had a trial at Hereford in the summer, impressed Hill during reserve outings against Tranmere and Preston.
Hill told the club's official website: "Marc will offer us something different because he is a good link player, something we perhaps don't have at the moment.
"He has some work to do to reach the tempo levels we have set in training, but we have seen something we like."