I did this also, when you save the voicenote you can then choose to make it a ringtones. I did this for my loud snoring friend. I record him everytime he passes out.
I have an AT&T 8310, but I only have a "send voice note" icon. When I record the only option I have is "send as MMS". Do I need to email it to myself to open it, or am a missing something?