Cannot be made into an Action in Photoshop CS4 and lower.
Another thing I like about this is that it's easy to erase parts of the lineart without losing it completely (Use the eraser tool on the layer, not the mask).Overview
1) Scan in lineart.
2) Create a new layer (Ctrl+Shift+N) and a layer mask.
3) Select All (Ctrl+A) and Copy (Ctrl+C)/Cut (Ctrl+X) lineart.
4) Alt+Click into the mask and paste with Ctrl+V.
5) Clean with levels (Ctrl+L) and brush tool (B).
6) Invert (Ctrl+I).
7) Fill layer with line color.My Other Tutorials[link]
Photoshop Comic Panels