A highside isn't saveable. But they all start off as slides, which usually means lowsides!
The difference is when the back starts to slip, if you snap the gas to WOT, you'll lowside. If you shut the gas off, you'll highside. There's degrees here, if you're only slipping a bit and do it, you might get a wiggle, you might get a full on slapper, and you might just get spit off entirely.
When the back end starts to let go, if the pavement is consistent (i.e., it's not sliding becuase of a grease spot on the corner), you can hold the throttle steady, and hang off slightly farther. This will have you get the bike a bit more vertical, which should give you a nice gradual increase in traction to help hook up. Some guys can let off the gas just a touch and have it come back without that fast transition that spits you off, but that's a twitchy and delicate skill there.
However, in no case should you cut your losses and hop off.
(NOTE LINK IS PROBABLY NWS* AND NOT FOR PANSIES WHO DONT LIKE BLOOD)
http://lifeisaroad.com/deerkilling.html
Big dresser hits a deer, the dude stayed on. Scary shit, but it's the same concept.
*NWS= if you're able to read the boards at work, you're probably okay. That is, if you get in trouble for reading that site, you'd probably get in trouble for reading this one too.