Unfortunately, xcode does not yet have support for importing OSX crash logs and symbolizing them. Therefore, you must use the command line and a little bit of manual work.
- Find your dSYM file.
- Assuming you are using xcode's archive functionality, open the Organizer window from the Window menu.
- Click the Archives tab.
- Right click on the appropriate build and select Show in Finder.
- When Finder opens, right click on the selected archive and select Show Package Contents.
- Navigate to the dSYM directory and copy the appropriate dSYM file to a temporary directory.
- Then navigate to Products, then Applications, and copy the app file to the same temporary directory.