I had the same problem on my iMac - Enabled iTunes Match it appeared to setup. Next day I launched iTunes and the process ran again. This time it got "stuck" or "hung" at step 1.
After trying a couple of differnet things, the "fix" for me was that I needed to re-create the iTunes Database:
http://support.apple.com/kb/ht1451
Ater re-creating the iTunes Database, the whole iTunes match setup completed in 4 hours - I have a 17K iTunes music library.
Here's a brief summary of how I would enable iTunes Match:
1. In iTunes, disable the Genuis.
2. Run the Disk Uility and rebuild the disk permissions.
3. Restart your Mac.
4. Re-create the iTunes database per the above referenced KB article.
5. In iTunes, enable the Genuis - wait for it to finsih BEFORE continuing.
6. In iTunes, enable iTunes Match.
7. When iTunes Match has completed setting itself up - you will see a completed screen that you click <Done> on.
8. Restore your iOS apps, books, custom rings tones, moives, TV Shows, etc. to the iTunes library. For some reason iTunes ony re-creates your music library and doesn't include any other media. It doesn't delete it, just doesn't recreate it in the library. You can manually add it by going to the following path:
~/Music/iTunes/iTunes Music
In the above ~ = your Users home directory on Macintosh HD
Once inside the iTunes Music directory you will see folders for each type of iTunes media. All you need to do is open the folders, select all and drag and drop into the iTunes Library in the iTunes Application.
9. Check for App updates for your iOS apps in iTunes.
10. Enable iTunes match on your iOS devices or other computers.
11. Enjoy
I followed the above and had success after running into problems.
I would also recommend that you DO NOT run any other appliactions on your Mac while setting up iTunes Match. iTunes says you can, but it slows down the setup process. It is somewhat CPU intensive and once you start uploading music to the cloud, that IS NOT in the iTunes store, it likes bandwidth.
