The bike is out of warranty. Probably no dealer involvement. Thought someone on this site might have an answer for this, seems like a pretty common thing to happen on the trellis frames during a get off, searched all the forums with no luck.
You are correct: it is fairly common with the trellis frame
when using frame sliders.
I'm fixing my Sport 1000 right now for this very problem. Mine was the result of a huge highside (racetrack) when my front touched the rear tire of a rider I was overtaking at about 90mph; I went sky high and the bike did the ol' launch... (wait for it)... end over end thing... it was messy! Broken collar bone and six weeks later I actually didn't realize the motor mount was cracked until after I had repaired everything else. I was cleaning what I thought was a hairline of grease/oil only to realize it was indeed a crack, then upon close examination saw that it ran all the way across the engine, across both case halves. Bummer.
In my case (pun not intended

) it turned out that what looked like a hairline crack was much more severe. In fact when we split the cases, a 3" long chunk fell off!
The only fix it is to disassemble the engine and have the cases welded. This absolutely must be done by a qualified welder! The shop that did mine is an aerospace machine shop who happen to be moto racing enthusiasts, so they really care about what they're doing. He pre-heated the cases prior to welding and did only a small amount at a time. He did the job over the course of the day so as not to warp the cases.
I don't know where you live, but if you can get your case halves to Phoenix, the company is called Superfinishers. if you need it, I can track down contact info tomorrow.
Also, I spoke to Mark Sutton at Ducshop near Atlanta, and he told me they repair four or five a year. You can send the cases to him.
A side note is Mark does not recommend frame sliders because of this problem. Ironically, I had heard that advice way back before my big get-off, but ignored it 'cause I thought the frame sliders looked cool! I won't be running frame sliders anymore (even though they do look cool

) baecause the tank got all banged up anyway, so between that, the clip-ons and rear-sets, it can just slide on those! This is probably a topic for another thread...
Anyway... DO NOT mess around with this problem. It is potentially life threatening. The engine is a stressed member so if it were to come loose, even just a little bit, could make for a lot of no fun! :eek
Too bad I didn't have a camera handy when we split those cases. You guys wouldn't believe it! The new weld job looks sound, but as the man who welded it said: "It should hold up, but it is NOT a new case." :think: