That rule was brought in to stop a possible restraint of trade challenge in the law courts, and allows limited movement outside the window.
Midfielder Guardiola had a trial with Manchester City in the summer but turned down their offer of a six-month contract. The 34-year-old's last club were Al-Ahli in Qatar.
Said the Latics boss: "I have spoken to Pep and I was very impressed that he knew so much about us. His experience would be a help to us."
Over the summer Jewell bolstered the squad with nine new signings, the latest being David Connolly who signed from Leicester for £2m.
And while content with what he has to work with, the Latics manager wouldn't mind adding another face.
Jewell said: "At the moment we are trying to get another player in who is not attached to a club.
"If we can get one more in, I'd be pleased, and we'll see if that happens in the near future.
"That won't stop our search for players, though, because it's vitally important for the next three months we scour the transfer market in Europe ahead of the next window in case we need reinforcing."
It might be Jewell returns in January for some of the targets he missed on this time, Trabzonspor striker Fatih Tekke being a player he was very keen to sign.
Three bids went in for the Turkey international but Latics were forced to abandon the chase because of the time scale involved as the deadline approached.
Jewell instead moved for Connolly and he feels the 40-cap Republic of Ireland international can make a big impact at the club.
He said: "I've seen David play often enough to know he can score goals and give teams plenty of problems.
"After his first morning of training with us on Friday you could see he was a natural finisher and I'm delighted to have him on board.
"Up front we know have the pace of Henri Camara, the strength and pace of Jason Roberts, and the predatory scoring instincts of Connolly."
The new signing himself is pleased to have got his Premiership chance at the age of 28, and wants to quickly start repaying Jewell's faith in him.
Connolly said: "I'm looking forward to the challenge and I want to be part of a successful strikeforce here.
"I'm excited by the Premiership, although I admit I've got here on the back of the hard work put in by the other lads.
"My aim is to work hard and try and help the club push forward and establish themselves in the league.
"The manager is very ambitious here and persuaded me to come. He and the chairman have taken the club forward and he wants to keep making progress.
"Possibly I was thinking my Premiership chance was slipping away, having seen a lot of players score a lot of goals in the Championship and not get the opportunity.
"I now have the chance with Wigan and intend to take it."
Latics returned to training this morning after the free weekend, although the squad was missing four players who remain on international duty.
Graham Kavanagh is with the Republic of Ireland squad for Wednesday's World Cup qualifier against France, while Leighton Baines and Ryan Taylor were travelling to Mainz today for the England Under-21 clash with Germany – neither were in the team which beat Wales 4-0 on Friday.
Josip Skoko is currently with the Australian side tackling the Solomon Islands in a two-legged World Cup qualifier – the Aussies won the first leg on Saturday 7-0.
Jewell said: "I hope they come back in one piece and not too tired to play for us.
"The first time they'll train with us this week is on Friday morning and then we'll be heading off to West Brom."