yes it is possible but is it worth the effort? and don't forget PG Music balance the RTs, add fx and such like to get the styles to sound 'just right'. you'll be guessing and it will not sound exactly the same as the Xtra styles.

as to the tracks that are missing maybe they are from bonus packs you didn't buy like the 49 pak. if you are supposed to have tracks and styles that you think are missing, log in to your PG Music account and they should be there to download.