Hi Manny,
the group below has probably already converted roland styles to yamaha. Conversions usually don't sound as good as they did on the original instrument.
http://groups.yahoo.com/group/yamaha-psr-styles/ I had a g800 years ago, and even though I have the EMC style conversion software,I've always done the following.
Before I sold one of my keyboards, I used to record each it's styles as a midifile ie Intro's, variations , fills, endings based on the chord of c & cmaj7. SOme Keyboards use MAj chords, some use maj7 chords as their basis.
Some keyboards have a midi to style function ( my VA7 & KN7000) ie you can create styles from midifiles. Yamaha doesn't have this feature but it has a huge user group, and a couple of the group members have written software to create styles from midifiles
I used to keep the midifiles as a backup, just in case the style I was trying to convert via the EMC software didn't work as well as I'd hoped. It's a lot more work doing it from a midifile, but if it's a style you use a lot, then it's worth it.
best wishes
Rikki