It's about 1 hour by car from Stockholm to Eskilstuna, I don't think there will be any "organized" busses but it's easy to travel by train (45 mins). From central Eskilstuna there will be busses to the arena.
Or...this link might help?(perhaps some leftover seats on that buss)
http://www.tptours.co.uk/GpTours/TourInfo....5-05-14_Sweden/
/ Ola