Terry, it's my pleasure to take the time to help the people who post here - this site is GREAT!, it's helped me a lot and I try to give back whenever I can.

So what you're trying to do is winterize only one part of your system. I assume that the waterfall pump has one line in (suction) and one line out (the feed for the waterfall). It shouldn't be hard to winterize just those 2 lines, though it's a little more tricky to do it if the pump is below the pool water level. Also, where is the 'feed source' for the pump (it's usually a main drain but could also be a suction port in the wall)? If you want to DIY, this info will help me advise you better.
If you are worried that you may not do it correctly, call in the pool dudes, but schedual it for a time when you are home so you can see what they do (so you'll be able to DYI in the future). Don't be afraid to ask them questions, they are in your employ and should be more than willing to tell you what they're doing and, why! It would probably be money well spent, however they will most likely be there less than 10 min (to blow and antifreeze 2 lines).
Whichever way you decide to handle it, please let us know what was done - we like to hear back from the folks we help - Waste