Billy Davies
And it is understood that Wolves midfielder Andrew Surman is among them.
But the Reds boss also challenged his current squad to step into the gap left by McKenna, who should find out the seriousness of his knee injury today.
"We are still in the process of talking to our staff, of identifying targets and seeing who is available," said Davies. "We are doing that as a matter of urgency.
"But this is a tough time of year to be trying to sign players.
"We also urgently need to look at the left-back situation. This is something you would ideally like to address in January."
Davies will await the results of a scan on McKenna's knee today, but if his medial ligament is damaged as badly as feared, it will spell the end of his season.
"Lewis McGugan did well when he came on against Swansea. He looked a different player to the one he did against Doncaster recently," said Davies
"He was working hard and chasing back and he needs to keep doing that. He can't just be a player who is good with the ball at his feet.
"He has been frustrated at being on the sidelines and he could get his chance to prove himself now.
"But he is not the only one who will have an opportunity in the coming weeks.
"There are other players who will have something to say about that position in midfield.
"Chris Cohen, Raddy Majewski, James Perch and Guy Moussi are all options and all will have to step up to the plate.
"James Perch can obviously also play at left-back, so there are options for us there as well.
"As I said at the weekend, now is the time for some of our unsung heroes to come to the fore. Whether we sign anyone or not, they will have a part to play."
Wolves midfielder Surman is believed to be one of the players Davies is considering making a move for.
The 23-year-old was signed from Southampton for a fee that could rise to £2m last summer.
He had built a reputation as one of the brightest young talents outside the Premiership with the Saints.
But he has failed to establish himself as a first-team regular at Molineux, starting only three Premiership games and making four substitute appearances.
Davies added: "The key at this time of year is who is available.
"Clubs do not generally want to part with players at this stage of the season."