Knitting cables without a cable needle is the perfect way to work cables that only involve four stitches or so. This tutorial will show you how to make a cable where the stitches on the cable needle would be held to the back, also known as a right-slanting cable.
The example shows what would be called a cable 4 back, meaning 4 stitches are involved. If it were worked with a cable needle you would slip 2 stitches onto the cable needle and hold it to the back of the work, knit the next 2 stitches, then knit the stitches off the cable needle (like so).
To do this without a cable needle, start with the yarn held at the front. Slip the first 2 stitches onto the right-hand needle, then move the yarn to the back.