For the alpha channel you will have to make a new one for each repaint you do. At the top of the 'layers' pallette is a folder called 'alpha' that is turned off by default. This contains all the layers used in the alpha channel. When you do a repaint you will have to copy any painted layers on your paint into this folder and find out just where in the 'stack' they need to be by trial and error basically but I put mine below the 'main' layer and above all stuff below the 'main' layer. The method I use is below....
1. Save your paint as a PSD file before working on the alpha stuff.
2.Turn on the 'alpha' folder by clicking in the box next to it's name then copy any paint layers into the 'alpha' folder and merge them into a single layer.
3. Select all the items on your new layer and set them to a grey level with the amount of 'shine' you would like. The more white the less shine. For painted areas I like to use a 5% grey and I use the 'fill' command to fill the areas with paint.
4. Turn on or off any layers you require in the finished alpha channel (i.e. turn off any 'Snooks' items so that they do not show on your paint).
5. In the layers pallette select 'Flatten Image' and then select the entire area and select 'copy'.
6. Go to the history pallette and delete the 'Select Canvas' layer and then the 'Flatten Image' layer so that you are back to where you were before.
7. Turn off the 'alpha' folder and click on any of your paint layers then click on the 'Channels' tab and select the 'Alpha 1' layer at the bottom.
8. Paste your copied alpha channel info into the 'Alpha 1' layer then click on the 'RGB' layer at the top to get back to the standard setting and then click on the 'Layers' tab.
9. Save your work as a PSD file with the new alpha channel.
10. On the 'Layers' pallette select 'Flatten Image' again and then go to 'Image\Rotate Canvas\Flip Canvas Vertical'
11. Now do a '
Save As' (this is
very important DO NOT do a 'Save' at this stage or you will be cussing for a week!) and select 'D3D/DDS (*.DDS)' as the format of choice. You will then get the following nVidia plug-in screen.....
Set yours up like like mine and you should be good to go.
Hope that helps.