It lies by Road 4 so if you come by car or a tourist bus one possibility is to follow Route 4/E60. If you choose this direction it takes about 3 hours to get to Hajduszoboszlo from Budapest. You might want to spend less time travelling, take the M3 and then after about 180 kms look for the signs for Debrecen and turn onto E79/M35. Though this way is about 30 kms longer, you can reach your destination 30 minutes earlier. And don't forget about the toll!
View Larger Map Budapest - Hajduszoboszlo
If you come by train, take the Budapest-Debrecen-Nyíregyháza-Záhony line. All the express trains stop at Hajduszoboszlo. There are 6 intercity trains and 2 international ones. During the summer there is a direct connection to Lake Balaton. If you are in to details you can find the exact timetables of MÁV (Hungarian State Railways) here.
If you come from further abroad you might come by air. Maybe you will arrive at Liszt Ferenc Airport Budapest, or Debrecen Airport. Hajduszoboszlo even has its own airport where small planes can land.