Tips & Tricks for Slip-stitch Cabling
For Certain Rows, Read Your Knitting, Not the Chart
When you are knitting the wrong side row using the "background" color, you can tell whether you need to slip a stitch or knit it without looking at the charts or pattern. For this row, simply slip stitches in the main color (the one you are cabling with) that were slipped the row before, and knit stitches in the background color that were knit the row before.
Cabling Without a Cable Needle – Slip-stitch Edition
Normally I dislike cabling without a cable needle because my stitches tend to make a run for it when I drop them for a bit. With slip-stitch cabling, however, the stitch you are cabling is usually not directly attached to the stitches nearby, so there is much less likelihood of the stitch becoming unknit and dropping down (as long as your yarn isn't too slippery!)
Cabling Front: holding a stitch in front of work
The first stitch on the left needle here is the one that will be held to the front.
Drop this stitch, and let it hang out in front of your knitting. It shouldn't go anywhere even when you pull on the next stitches by knitting them because it's not attached to them.
Once the required number of stitches have been knit from the left needle, use the left needle to go pick up the waiting stitch at the front of the knitting.
Pull the stitch into position and knit as usual.
Cabling Back: Holding stitch(es) in back of work
The first two stitches on the left needle will be the two that are held in back for the next cable cross.
Drop these stitches and let them hang out behind your work. Again, they won't go anywhere because they aren't under any stress. You may need to nudge them to the back as you knit the next stitch so they are out of your way.
Once you've knit the stitch that needs to cross in front, you can pull the right needle forward and get a better look at them...
... then pick them back up with your left needle.
Pull them back into position, and they are ready to be knit to complete the cable cross.