Waddock told the club's official website: "We will be able to look at both players over the course of the month and assess the situation from there.
"Alex has arrived because we are no nearer knowing when Nikki Bull will be fit again. He requires a further scan on his groin problem and it's possible he will be sidelined for longer than we first thought.
"With Chris Blackburn already out of Saturday's visit to Port Vale due to suspension, it was also important to introduce Andy to the squad.
"I was hoping that there would be further business conducted before the transfer deadline but that is unlikely. However there is a week's grace and then the loan market opens up again."