The experienced striker is keen to get back to first team football after making a three-month switch from Swansea City recently.
His arrival gives Blues boss Lee Clark an attacking quartet of Marlon King, Nikola Zigic and Peter Lovenkrands, as well as Lita, to call upon, a big test for Forest's new-look defence.
'It's good to have that in the group,' Lita told the Birmingham Post.
A difficult start to life in charge for Clark was helped somewhat by a 1-0 win over Peterborough last time out.
Forest's own striker signing meanwhile is keen to play in the game despite suffering an injury on international duty.
Simon Cox has only slight ligament damage, sustained playing for Ireland on Tuesday, rather than a feared broken metatarsal.
"I must admit the alarm bells rang a little when I heard he had been stretchered off but touch wood he's bright and there's no obvious fracture, so we'll see what he's like tomorrow [Friday]," manager Sean O'Driscoll told the club's official website.
"He's desperate to play on Saturday and we were surprised when he came walking through the door this morning. I expected him to be on crutches but he walked in fine."