The former Luton frontman has not been able to hold down a regular first-team spot this season and boss George Burley wants him to get some game time with the Lions.
"We think it is a good move for the boy," Burley told the Croydon Advertiser. "Calvin hasn't been able to get regular games for us and we think it's important for his development to playing more often.
"We'll know for sure if he's going to go on Thursday, but at this stage of his career he needs to be playing matches."
Millwall have been hit by injuries to attackers Chris Hackett, Kevin Lisbie and Theo Robinson and are also bringing in Southampton winger Jason Puncheon on loan.
Source: PA
Source: PA