3a - How to setup Spot Color Channels in Adobe Photoshop?
Please make sure you are working on a duplicate of your original art as the final outcome of these processes will make that file unusable for other purposes.
Step 1: Open the art file in Adobe Photoshop.
Step 2: Click the New Channel icon on the Channels Pallet.
Step 3: Double click the Alpha Channel.
Step 4: On the Alpha Channel Dialog Box select Spot Color and click on the Color Swatch.
Step 5: Click Color Libraries on the Color Picker Dialog Box.
Step 6: Choose the PMS Color you want that Alpha Channel to be.
Step 7: Click OK on all Dialog Boxes to get back to the Channel Pallet.
Step 8: Repeat steps 2 through 7 for each additional Spot Color needed.