To have accompaniment exactly like the original, you'll need to sequence the song - note for note, instrument by instrument. With an arranger keyboard like PA50, you'll not be able to achieve that as the styles are pre-programmed.
Furthermore, you'll need decent sound quality to match the original.
It's not impossible to make it almost the same as the original. I've done it many times. You'll need either a workstation (keyboard with sequencer built-in) or a software sequencer (like Cubase or Sonar). For sounds, a good keyboard may give you close to what you need. Otherwise, you may need to expand the sound via sound modules, or software plugins. Simplest way is to get a workstation (eg. Yamaha Motif, Roland Fantom, Korg Triton etc).
These are the hardware requirements. Next, you need a good ear to transcribe the original piece into notation - instrument by instrument and note for note. Then you'll need to sequence it. Sequencing skills is the final step - bad sequencing makes it sound like cheesy computer music. While sequencing is not difficult in itself, getting a sequence to sound good require experience. You'll have to play around with it and experiement.