Whether you hold the cable needle to the back or front depends on which way the cable has to slant. Your directions should tell you that. It doesn't sound like a simple cable, so if you're not sure, maybe you can either post a picture or put the exact directions here?
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry