Hi Chas,
which keyboard do you have?
Some do have functions where you can copy style phrases ( Bass, drums ,strings etc )& mix n match to create new style parts, but phrases are better suited to variations and fills, because a lot of intro's & endings have chord progressions.
Some keyboards allow you to copy complete style parts like an intro, ending , fills variations etc. & you can mix n match that way.

My Ketron sd1 has this copy function.

Yamaha's I think call it Style Assembly. and if you're actually a psr owner, OMB software could be used for this function ie you can save phrases from style parts and import them into existing styles or create completely new ones.
You could even put together a library of intro's , endings etc etc that you could import into different styles.

Not quite as versatile as what you're suggesting, but the copy function does come in handy.

best wishes

Rikki

[QUOTE]Originally posted by cgiles:
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[This message has been edited by rikkisbears (edited 06-06-2006).]