I think you just have to put the things you want in B/W on layers with pen color black, and the color things on layers with the pen color set to whatever color you want, right? That's for lines.

But you said "colour images" - I plotted a drawing of a gallery interior once - architecture in B/W, paintings on the walls in color. Each painting was a raster image, and all the raster images were on a layer that I set to print in color - I think I set that layer to "object color" - is that what you're trying to do?

Thats exactly what I am trying to do. Plot the plan with notations corisponding to images of furniture and finishes.

I remember it being an easy but very nit-picky process. It's been a few years ago, on CAD 2000 probably - maybe it's easier on a newer version?

I probably plotted 20 times to get one decent sheet...

like liberty bell mentioned, set the pen assignments to black and whatever lineweights you want. The images, even if on a layer which is black will plot in colour (provided your default print settings don't have any grayscale option checked).
if you don't want black borders/frames around teh images you can use the command IMAGEFRAME and set it to OFF. Everytime you need to move the images though, you'll have to set IMAGEFRAME to ON to select them.

its very easy. open the plot style editor>select all the colours and choose pen colour black, and set the lineweight to 0.1
Then chose individual lineweights for each of the colours that you have used in your drawing layers. Like i said, images will plot in colour as long as you rprinter is set to print in colour.

you might have an easier time printing to a pdf, i did what you are trying to do and i had no problems.