depends on how handy you are. and they may be able to tap the line before it hits the softener.
the problem I see with any bypass, built-in or added, you lose the convenience of your water heater. you'll be bringing in cold water. I think the best way is to use your built-in bypass at your sink. let it run cold there for a bit, until you hit hard water. say about a minute. and then go ahead and use the hard cold water and the softened hot water to bring it up to temp. even if you're trying to hit 80-degree water, you have probably 50 gallons of hot water to use. and you won't use that much hot vs cold. so, wouldn't worry about a small amount of softened hot.