The former West Ham defender has not played competitive football since 2009, when he was the victim of a brutal stabbing incident incident, but has been training with Leeds in recent weeks.
And Whites boss Simon Grayson maintains he will be keeping tabs on the 27-year-old's progress.
"Calum obviously feels it will be beneficial for him to play competitive football rather than reserve team football somewhere or training," Grayson told Leeds' official website.
"I hope this is the case for him and helps him. I initially said it was all about looking at his fitness and that could take weeks or even months. There was no time-scale.
"We'll keep an eye on him and see where he is in terms of fitness and how he goes on."
Source: PA
Source: PA