I am a big fan of this software for Windows. It only has one real competitor on the Mac side, NZB Drop by Asar (http://www.asar.com/nzbdrop.html), which doesn't come close to the functionality of Newsleecher.
I ran this under the latest two versions of Crossover I have used, 6.2.0 and 6.2.1, and it installed and ran just fine, with just three very minor and slightly weird behaviors.
First, as you would expect with most small downloaded utilities, I had to run the Newsleecher installer manually with the "Run Command..." command. After that it didn't automatically create the program file aliases (shortcuts) I needed, so I had to do that manually. Not a big deal at all, but be aware you might not see that your install did anything at first unless you manually run it the first time.
Secondly , it did not find its own temporary folder because it was set to use the shell variable as a root for its temp folder. The only result of this problem was an error message informing me it couldn't find it's own temp path, and telling me it would use the default windows temp folder instead. This setting can be configured from within Newsleecher's own 'Options' panel so my solution was just to set the temporary folder to a folder on my Mac's local disk.
Finally, this program does not work if you minimize it to the tray or set it automatically to open in the system tray. This is a minor bug but you should be aware that Crossover wasn't able to show me its tray icon at all, even after I configured my bottle to show tray icons in a floating window.
Generally speaking, it pays to go through the 'Options' panel and set your default Temporary, Download, and NZB Scanning directories manually when you install it. Once you do that, the program is fire and forget. Mine now scans and reads NZB files from a folder at in my /Users/MACUSERNAME/Downloads/NZBs/ folder, downloads them to /Users/MACUSERNAME/Downloads/, then moves the NZBs into another folder so I know they've been processed.
I haven't tested the supersearch functionality at all.