well i found this it might help you..idk if you need a memory card or it might just save to the razr hard drive..but anyways try it cuz im to lazy to grab my razr lol.
http://motorola-global-eng.custhelp.com/cgi-bin/motorola_global_eng.cfg/php/enduser/std_adp.php?p_faqid=8961
Well that will allow you to put on mp3's.. To put on ringtones, you will need a program to crop the mp3. Try wavepad, google it. Just load the mp3, and drag the little bar over what part of the song you want, and delete the rest, then re save it..Try it and good luck:) if you need any more help, just ask me. but im just guessing so idk if it will work or not.