How can I draw a "real" dotted line?

I want a simple dotted line (hor/vert. only, no diagonals) drawn in a canvas.

I tried setting canvas.pen.style := psDot, but the Windows  'dot' style
is really 2-3 pixels per dot, and I want a 1-0-1-0-1-0-1-0 pattern ala
Mac Plus 50% gray. Every other pixel drawn, that is.

Do I have to create a 1-pixel wide rectangle and fill it? Or step through
every other pixel and set it? Thanks!

- Matt