I just create a quick webpage with links to various MP3 ringtones and the following instructions:
1) Please click on a ringtone below.
2) Once it has completed downloading it will play automatically in the media player.
3) If you like the ringtone press the menu button and select Save from the menu.
4) If you phone allows it, check the Set as Ringtone box and click the Save button. Otherwise you will be able to access this saved ringtone under the settings for Profiles.