And long queues at the ticket office in the last couple of days suggest the Wigan public are now backing the club in their numbers.
Jewell said: "There should be a massive atmosphere inside the JJB and the supporters have their part to play.
"We want the stadium bouncing because when our supporters make a noise, it doesn't half make a difference.
"On Sunday I'm asking both the players and supporters for one last big effort because they have been superb all season."
Latics have room for 16,000 of their own fans in the ground, with the whole of the East Stand reserved for visiting supporters – segregation doesn't allow the stand to be shared at the moment.
At the start of business today, there were only 3,000 seats left for Wiganers, and officials believe all will be snapped up before the game.
It would mean a record turnout of home fans at the JJB, comfortably beating the 13,605 for the Ipswich game in March.
Reading have so far shifted 2,000 of their allocation and the fixture is now all-ticket to prevent home fans trying to gain entry into the East Stand.
Latics' head of communications Matt McCann said: "We are heading for a sell-out as far as home fans are concerned.
"If people wait until the day of the game having decided they will pay on the turnstile, they are likely to be disappointed.
"Latics fans are going to have to get used to buying tickets in advance for matches because that is one of the trappings of success.
"As we found for the away game at Preston last week, demand is now outstripping supply, and it looks like the same for Sunday.
"In the past, fans could turn up five minutes before kick-off and walk on but that won't be able to happen for much longer."
Meanwhile, Jewell says his full concentration is going on Sunday's match rather than the prize that may lie beyond it.
If Premiership football is booked, he admits time will be at a premium when it comes to strengthening the squad.
Jewell said: "I know which players are good enough for the Premiership, which aren't, who is available and who isn't.
"We might have to go a bit more down the European road, I don't know, but let's get over the line first.
"If it does happen, we haven't got a lot of time because of the transfer window. As soon as the game is over on Sunday should we get a positive result, we will be planning for next season.
"Until then, all our energies must go on preparing to play Reading."
FOZZY HAS THE EDGE OVER WIGAN - Reading Evening Post
BEWARE THE BOGEYMAN – Royals striker Nicky Forster has a fine record against Wigan and is pictured being congratulated by Steve Sidwell after scoring in Royals’ last game, a 2-1 home defeat by Wolves on Saturday
NICKY FORSTER will be hoping to continue his match-winning heroics against high-flying Wigan Athletic and clinch a play-off place for Reading
The pacy striker has been a bogeyman to the Latics over the years. He netted both goals in a 2-0 win at the JJB Stadium last year, as well as breaking Wigan hearts in the 2001 play-off semi-finals.
Royals looked down and out when Fozzy came on as a substitute and turned the game in the final four minutes to book Royals a place at the Millennium Stadium.
Should he deliver the killer blow again on Sunday (1pm kick-off), it will be the ultimate irony as he nearly signed for Wigan in March.
The deal was only scuppered when manager Steve Coppell insisted on a clause banning him from facing Reading in the Championship or any play-off matches.
And Fozzy said: “It’s strange I could have been at Wigan. It was a similar situation to the Sunderland match. But it never actually got as far as me going up there and talking to them. I have the greatest respect for both clubs, but my loyalty lies with Reading and I’ll be doing everything I can to get us the win.
“I have done well against them in the past such as in that play-off game and I also scored twice there last season.
“That was probably the highlight for me last season as I then had problems with my stomach. Until recently that was the last time I really felt comfortable and was on top of my game. Hopefully I can do well again.”
Royals need to better any result rivals West Ham achieve at Watford, or hope Preston beat Derby if they are to gate-crash the promotion play-off party.
Wigan, though, know victory will secure second spot in the Championship and a place in the Premiership next season.
Forster said: “We have to go and beat one of the leading teams at their place and rely on someone else doing us a favour really.
“But we have much more of a chance than last season when we were hoping for two or three results to go our way on the final day.”
“We have made it difficult for ourselves after losing to Wolves. But we have a feeling it is still achievable. We just have to do it the hard way.”