Pesonally I would just use my wacom and a small soft brush to draw them. You can use the color picker to make sure what you are drawing matches the existing color.

If you do not have a tablet, and are not comfortable drawing freehand with a mouse, you could use the pen tool to create a curve for each lash and then use the stroke command under edit. I would do this on a separate layer so you can control the opacity and have the option of playing with the blending modes.