What is your "long" method, exactly? I'm curious...:think:
Ok, I tried this in PS7. Should work the same in PS8.
Create a new image sized 2 X 2 pixels with white background. Select the fixed sized marque tool and set it to 1 X 1 pixel. You'll need to zoom in to 1600% to see the image better. Create 2 selection boxes (1 X 1 pixels in size) at opposite corners of the 2 X 2 pixels image. Press and hold [Shift] as you select the second area at the opposite corner. Fill the selection with black. You'll end up with a checkered image.
Press [Ctrl]+[d] to drop the selection. Go to main menu "Edit", "Define pattern". Enter a name for the check box image. This black and white check pattern will be used as a layer mask to hide alternating pixels (black pixels in the layer mask hides).
Now, open your actual image. Select the layer containing the image of interest (duplicate it if it is locked and hide the locked layer). Go to main menu "Layer", "Add Layer Mask", select reveal all. Then go to main menu "Edit", "Fill" and fill the layer mask with the newly created checkered pattern. Now, half of the pixels are invisible.
If you want to interweave another image, just create another 2 X 2 checkered pattern with the black boxes on the other corners.
Hope this helps.