1.- Open Logic Pro X and create a New Project. Click the Add Tracks + button located above the track headers to open the New Tracks dialog (When opening a new empty project, the New Tracks dialog will appear automatically).

  

2.- The New Tracks dialog will prompt you to choose a type of track. Select Software Instrument and click Create.
 

3.- A new software instrument track will appear in the Track area. To load a Syntheway plug-in, make sure the Inspector is shown and that the Logic Library is hidden. To do so, click on their respective icons in the Control Bar to the upper-left side of the Main window. The Library symbol should be greyed out and the Inspector symbol highlighted. In the Inspector, you will now see the software instrument track's channel strip.

  

4.- In the software instrument track's channel strip, click the Instrument slot.

5.- Browse through the drop-down software instruments menu and select the Audio Unit from the Syntheway menu

After loading the plug-in, its interface will open automatically. If you wish to open it again after closing its window, click on the plug-in name in the channel strip, in the Syntheway Plugin.