To install the Auto Patch Advance MIDI FX Script, unzip the downloaded package and move the file named 441K Auto Patch Advance.pstto the following below. You will have to create the Scripter folder if it doesn’t already exist.
~/Music/Audio Music Apps/Plug-In Settings/Scripter/
After installation, Auto Patch Advance can be found in MainStage 3’s Scripter MIDI FX plugin dropdown menu.
Auto Patch Advance is a MIDI FX script that lets you assign MainStage’s patch change function to any MIDI note. By default, a MIDI note doesn’t sound when its also assigned to advance patches. Auto Patch Advance solves this problem by creating addressing a virtual footswitch.
Setting Up the IAC Driver
The IAC Driver is a virtual MIDI routing device built into Mac OS X. It can be used to send MIDI data between software applications without the need for another external hardware device. To set up the IAC Driver, open up Audio MIDI Setup.app, which can be found under Applications/Utilities/.