HelpMinecraft script for alts

I'm looking for someone to make me a script or help me make a script to have minecraft alts join a server they don't have to spam the server just join it, if someone could please help me out!!

I have two different operating systems but prefer Mac

Weepcraft used to have a tool like this.
But it used random non premium usernames on cracked servers.
but I'm not sure if it still in the client

I need this too!!!!

I have a bot that can do this, if anyone is interested add me on skype at prefix_9, its not 100% finished yet but its like 95% done. If you want to see it working I made a video of it a little bit ago here:

EDIT: Btw its not in any client, its an external java application.