2.2 froyo - How do I set a custom MP3 as a ringtone for other notifications?

I have an HTC Droid Incredible running Android 2.2 FroYo and would like to use custom sounds/songs as ringtones for text message notifications, event and task reminders, Facebook and Twitter notifications, and email messages. I have the MP3s that I want to use located in the /ringtones directory of my phone, but they don't show up on the list of possible sound effects/tones/notifications, but they do show up in the selection for incoming call ringtones. What do I do to use them?

Answer

Put the sounds in the /media/audio/notifications folder on your SD card. Create this folder if it doesn't exist.