Here's a little video I put together to show how to cable WITHOUT a cable needle.
Sometimes though a little explanation is necessary for clarity.
For a CF (cable front) with this technique you go UNDER the first part of your cable stitches (ex.: C6F- skip the first three stitches, go behind them and knit the next three stitches, then knit the skipped stitches and let them all fall off the left needle. No worries they'll be on the right needle all nice n twisted). One more thing with this technique, if you're making traveling vines or cables (half knit half purled) you would have to knit all the stitches for the CF. But don't worry those ones that are in back are hidden anyway.
For a CB (cable back) you would go OVER the first part of your cable stitches. (ex.: same as above, skip the first three stitches, go IN FRONT of them and either knit or purl (whatever the pattern says) the next 3 stitches, then either knit or purl the skipped stitches. Let them all fall from the left needle. They will be on the right needle all nice n twisted.
Hope that helps ya hun.