Actually, the easiest way to do it is with the included MotoCast sync software. Install it to your computer, then when you connect it, you have an option to sync playlists/music from your iTunes.
I wish I could tell you the exact application to use, but I feel that Moto includes like two to three different MotoCast apps for your computer. To install them on your comp, plug it in with USB and make sure its USB Mass Storage...then you should be asked to install MotoCast.
Then, you can Sync Photos, Music, Videos and Podcasts from your computer really easily. The software will pull your iTunes information and allow you to Sync the music to your Razr. (Keep in mind that it will not transfer DRM music).
I wish I could give you more help, but if you have questions, let me know...I'll try and help you out the best I can!