The R24 should have a folder on the SD card called project, with a subdirectory called something like PROOO and under that a folder marked AUDIO. That folder will have the .wav files from the recording. As long as you aren't using internal effects like reverb or guitar sims etc, you should be able to just copy them to your hard drive and dump them directly into Studio One.
If you used any effects in a mixdown situation, those effects won't be there, of course. If it was particularly critical to the project, you could render those tracks which need modifcation and then copy the remaining files over. A bit of a pain, but it keeps the modified track intact.