macOS Venture - Custom iMessage alert?

[VTGuy79]

How can I add a custom alert for new imessages? I've read several different options but I just can't copy the file to the sounds folder.

 

[BrianBaughn]

I don't think you can anymore. You can add AIFF files to ~/Library/Sounds and use them for alert sounds in your particular User Account but the Messages app only looks into areas of the non-editable System folder for its text tones.