Villa lost in the play-off final to Fulham a year ago and the manager Dean Smith said it was a case of practice makes flawless when it came to the spot-kicks.
Jedinak's penalty helped Villa win the shootout against West Brom.
Villa won the first leg 2-1 at home but Craig Dawson's first-half header levelled it up for West Brom.
The final is at Wembley Stadium on May 27. "All of us are very hungry".
The hosts had Chris Brunt sent off with 10 minutes of normal time remaining but keeper Sam Johnstone made a stunning reflex save to deny Albert Adomah and take the tie into extra time.
Despite this, he came up huge for his team in the shootout, saving from both Mason Holgate and Ahmed Hegazi, West Brom's first two takers.
They will face Leeds or Derby, who meet at Elland Road for their second leg on Wednesday night, with Leeds leading 1-0 on aggregate. "We practice penalties, so I think I must've faced a 100 a day the last few days".
Villa missed out in the playoff final previous year, losing 1-0 to Fulham and Grealish, who has been linked with a summer move to Tottenham, is keen to make amends in what could be his final game for the club.