Digital BW, The Print

Followed the excellent document by Roger Sopher, I have successfully 
installed QuadTone RIP on RedHat9. But the qtcups utility suggested 
by Roger's document doesn't give me the options to print my image 
with a specified size in terms of width and height. It only gives 
scale percentage and paper size options, but I want to have a precise 
output size field to specify, similarly as in Photoshop print-preview 
utility. I found GIMP has the print layout utility I want, but it 
prints strange ASCII characters even though I chose Photo option and 
pointed to the Quad1280 printer I created. Roger's document doesn't 
mention GIMP print utility. I guess Roger encountered the same 
problem and therefore suggests we use qtcups instead.

So my question for those who use QuadTone RIP on Linux: how do you 
accurately control the print size and layout?

Thanks in advance.

Chao