The Retro-AS1 RTAS plugin is available with Retro-AS1 version 2.1.3 (or higher). If you do not have this version of Retro-AS1, you can download it at bitheadz.com
1. Once you have downloaded the update, double-click the installer to update Retro-AS1. Be sure to select the original Retro-AS1 folder to install the new version into.
2. Verify that OMS automatically detects the Retro-AS1 driver.
3. Quit all applications, and open the Retro-AS1 folder
4. Inside the Retro-AS1 Utilities folder, locate and open "Retro-AS1 Utilities". Within this folder, locate and open the "ProTools" folder.
5. Move the "Retro-AS1 RTAS" plugin to your desktop, and close other folders.
6. Inside the Macintosh HD, locate and open the System Folder, then locate and open the DAE Folder.
7. Inside the DAE find the Plug-ins folder. Drop the Retro-AS1 RTAS plugin from the desktop into this Plug-ins folder. Close all open folders.
8. From the apple menu, choose the Control Panels sub menu, and select Retro-AS1.
9. In the Retro-AS1 control panel, set "Default MIDI Input" to "OMS". Set "Audio i/o" to "Plug-in".
Close the control panel, and click YES to save changes.
10. Launch ProTools (open a session or create a new session).
11. From the File menu, choose New Track and create a MIDI track. Repeat the step, the second time creating an "Aux Input".
12. Assign the MIDI track's output to Retro-AS1 and select a channel (1-16), then record enable the midi track.
13. Set the Aux track's input to any input, and it's output to your main outs.
14. From the Aux Track's insert list, choose Plugin >>> Retro-AS1. Use the Retro-AS1 Plug-in to choose a bank and a sound.

Audio from Retro-AS1 is routed through the Aux track out your ProTools hardware.