Forwards DJ Campbell, Jermaine Easter and most recently Steve Morison, who sustained a neck injury in Tuesday's defeat at Blackpool, are all currently struggling with problems.
Maierhofer, who stands at just under six foot eight inches tall, has been without a club since leaving German side Cologne last summer.
The 31-year-old has had previous experience of playing in England having featured in the Premier League for Wolverhampton Wanderers during the 2009/10 season after a £1.8million move from Rapid Vienna.
Maierhofer trained with his new team-mates on Thursday and will wear squad number 42 as the south Londoners strive to retain their Championship status.
Meanwhile, the Lions have recalled another striker John Marquis from his loan at Northampton early after seven appearances for the Cobblers while young defender Will De Havilland has joined Histon on a youth loan until the end of the season.