XP60 didn't have styles... Those are sequencer files.
I don't know for sure, but I would imagine there is a tool to convert them to SMFs somewhere (Google, anyone?).
Once in SMF, a G800 will play them as sequences, but to convert them to styles, that's a much more involved process (and I'm not sure you really want them as 'styles', do you?).
EMC software MIGHT be able to convert them into styles, but if all you want is for the XP60 files to play on a Roland, well, they are not styles in the first place...
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An arranger is just a tool. What matters is what you build with it..!