Best way to create custom text message ringtones?

Use SSH and replace one of the .aiff files with your custom one.

 

Bitesms will let you choose any ringtone you have as an SMS tone

 

I use diskaid to ssh into my phone and I use "switch" to convert the aiff files to caf. It takes about a minute to actually make the custom tones. Remember not to make the sms tone too long because it will play even if you open up the message.

 

tonefxs for ALL tones......can change on the fly easily,also can setup rotating tones.

nice app from cydia

 

I used this for for randomizing my ringtones. It was great.

 

Or if you don't like replacing system files, make them use winterboard. Put the sound file with the system file name you want it to replace into Themes/(Custom name)/UISounds/. Then just activate it through winterboard as if it were a theme.