The qualifier will be played on the Gold Coast on Friday night and the Heat will not having batting big guns Colin Munro or Sam Billings, who have joined their T20 sides in the UAE.
The winners of the sold-out qualifier will host the final on Wednesday.
The Heat won the 2012 final against Perth at the WACA, their only title, but have never hosted a final.
Bowlers Paul Walter, Matt Kuhnemann and Xavier Bartlett made the BBL team of the tournament. However, none of the Heat batters made the side, and Munro is the only Heat batter in the top 20 run-scorers for the season.
That fact does not faze McSweeney. Walter and Bartlett are both handy with the bat, and allrounder Michael Neser recently made a match-winning 64 not out against the Scorchers.
Brisbane Heat allrounder Michael Neser can have a massive impact with the ball or the bat. (Morgan Hancock/AAP PHOTOS)
"All year everyone has contributed with the bat. We weren't relying on Munro, Billings, Marnus (Labuschagne) and Usman (Khawaja) the whole time," McSweeney said.
"Neser played an unbelievable innings that won us the game the other night, and Xavier has done it before. Paul Walter has made runs.
"The confidence is that no matter who we have out there, we can get the job done.
"Max Bryant and Jimmy Peirson came in last game and they have had great performances at Big Bash level already. There is no reason they can't do the same tomorrow."
An unknown quantity is the drop-in pitch and how it will play, with the Gabba being prepared for the second Test against the West Indies.
The Heat have a poor record against the Sixers, with five wins and 13 losses.
"A lot of us played last year when we beat them at the SCG on their home track, and that is still in our memories," McSweeney said.
"To have a home (decider) would be awesome. Hopefully we can put a good performance out there and host that final next Wednesday.
"The wicket will be slightly tricky as a batting group, but we have a sell-out in front of a Queensland home crowd."
The 24-year-old is regarded as one of Australia's brightest batting prospects and is ready for the responsibility of being skipper in the absence of Khawaja and Munro.
"As a kid I was always captain of the junior teams coming through, and when you are not captain you are thinking like a captain," McSweeney said.
"I have plenty to learn and I have tried to be a sponge learning off Colin Munro, Jimmy Peirson last year and Usman Khawaja.
"Hopefully I can do a good job and contribute to a win."
