Excuse my naivety but would it be possible to hack a laser printer driver/firmware to implement custom dithering instead of the embedded default ones?
If its a PostScript laser printer then you might be able to use the sethalftone operator to use a different threshold array for the screens.
If you actually want to use dithering or something instead then you would need to actually 'hack' the code. I've no doubt its possible, but it would be enormously difficult and to my mind fairly pointless.
If you don't like the technique in your printer then use something like Ghostscript to render the PostScript to a grayscale image, apply the technique you like, then wrap the resulting 1 bit per pixel image back up as PostScript and send it to your printer. Because the image is now monochrome no further screening will be applied.
If you are talking about colour then you can do the same, but you'll have to produce separated output and recombine the halftoned images into one.
I should probably point out that printer manufacturers usually expend a reasonable degree of effort in getting passable quality output, taking the characteristics of the print technology into account. I won't say its impossible to do better, but you'll have to have a good idea what you are doing.