Googling led me to this page where the author had the same problem, and they found a solution in Safari Bookmarks Extractor. I can't test that it still works with version changes in both, but it probably does. Once you have your extracted bookmarks, you just use Manage Bookmarks -> File -> Import -> From File.
Off topic I know, but I know that sites like xbox-scene.com were flooded when the system came out. Recently made systems are being made more stable it seems, but it's still a major issue to anyone that bought one around launch.