Does your pattern tell you anywhere what they want you to do for the "single cable stitch"? You can't make a cable out of one stitch. Do you have a link to the pattern on-line or can you give us a few rows and the number you cast on?
for a scarf you might want to do a stitch that looks good from both sides...
maybe you can explain a little further what your intention is. Then we might have more proposals.
For the cabling one over one ( a cable where every "band" of the cable is 1 stitch wide and the cable all together is 2 stitches wide): do it like Suzeeq said. Just learn it and do not use a cable needle for the small ones. Too much efford for the same result.
Continental Knitter with passion, pretty busy and always onto something new.
I have been away from the forum for a bit, but I am still around!