Horizontal Scanlines
1. Create a 1 X 3 Document make sure its transparent
2. Zoom in and put a black dot in the middle
Like so:
http://img164.echo.cx/img164/4406/scanlines8rr.png
3. Edit>Define Pattern
Diagonal Scanlines
1. Create a 3 X 3/2 x 2 document make sures it transparent
2. Zoom in and put a diagonal lines from corner to corner
Likes so:
http://img98.echo.cx/img98/8695/dia1qk.png
3. Edit>Define Pattern